Full List of Policies

The policy explainers were written by Sam Ratner, Ethan Winter, Meredith Conroy, Kevin Reuning, and Colin McAuliffe

Note, cosponsorship counts only include voting members.

Foreign Policy

The 115th Congress saw action on three major progressive foreign policy priorities: ending the forever war, enabling close oversight of the defense budget, and offering reparations for past war crimes.

The most fundamental foreign policy shift sought by congressional Democrats was a repeal of the Authorization for the Use of Military Force (AUMF), the absurdly broad post-9/11 law that presidents have used to justify military deployments from Kenya to the Philippines. Rep. Barbara Lee has introduced a bill to repeal the AUMF almost every year since it passed, and in 2017 her ominibus amendment to give the AUMF an eight-month sunset clause came so close to passing that Paul Ryan had to resort to rules shenanigans to prevent it from coming to a vote.

If passed, an AUMF repeal would be a watershed moment for Congress--and congressional progressives in particular -- reasserting power over questions of war and peace. After years of giving the president a blank check to call just about any military action part of the “War on Terror”, a more restrictive post-AUMF authorization would allow Congress a chance to put an expiration date on the forever war.

In addition to the AUMF repeal, we also included two more specific efforts to end American involvement in disastrous conflicts in the Middle East. 185 House Democrats (and 15 House Republicans) had their resolution to end American support for Saudi Arabia’s genocidal war in Yemen undone by five Democrats who somehow thought pulling out of an incredibly unpopular war would endanger the Farm Bill. The resolution is likely to pass the house in the 116th Congress, but every extra day the war in Yemen drags on more Yemeni children die from criminal Saudi airstrikes abetted by American tax dollars.

Barbara Lee also introduced legislation to prohibit American ground troops from deploying to Syria, an attempt to limit both the military adventurism beloved of Trump administration figures like National Security Advisor John Bolton and the chances of further confrontation between American forces and Russian and/or Iranian forces in Syria.

The results of the first ever full Defense Department audit were released last year, and to no one’s surprise it failed miserably. Of the 21 investigations into different aspects of the defense budget that went into the audit report, only five resulted in a passing grade for Pentagon bookkeepers. Barbara Lee (you may sense a theme here -- no one has been a more active leader on progressive foreign policy priorities) introduced legislation to force the Pentagon to conduct a full audit each year, on pain of a significant cut in defense spending. If passed, the bill would finally bring scrutiny of military spending to a level approaching that applied to social spending, allowing Congress to make better decisions about spending priorities.

Finally, we included Barbara Lee’s Victims of Agent Orange Relief Act, a bill that grows out of efforts by Vietnamese and American activists to secure reparative justice for civilians and soldiers alike harmed by America’s use of toxic herbicides as a weapon of war in Vietnam. The bill would fund health care and services for uncompensated victims of Agent Orange and their children, as well as cleanups of contaminated land in Vietnam. The US has a long history of ignoring wrongs it has committed around the world, but the cause of internationalism depends on honest reckonings with the past to build trust for the future. Fixing some of the harm caused by Agent Orange is a good place to start.

Agent Orange Relief: 26 cosponsors

Repeal the AUMF: 31 cosponsors

Prohibit Combat Troops in Syria: 33 cosponsors

Audit the Pentagon: 38 cosponsors

Prohibit Military Assistance to Saudi Arabia: 30

End US Involvement in Yemen: 5 members voted to continue US involvement

Social Insurance and Anti-Poverty

Democrats in the 115th Congress introduced several bills which expand or enhance existing anti-poverty and social insurance programs. Of those, the most commonly cosponsored program is Social Security expansion. We consider Democrats to be supporters of Social Security expansion if they are a cosponsor of either the Social Security Expansion Act or the Social Security 2100 Act. These two bills are similar in that they both expand benefits and increase the cap on income that is subject to the payroll taxes that finance benefits.

The Earned Income Tax Credit is an anti-poverty policy that subsidizes the incomes of low wage workers. There are quite a few flaws with this policy, but two Democratic proposals have been introduced to shore up some of those flaws. The GAIN act increases the amount of the subsidy, and the EITC modernization act expands eligibility to students and caregivers (who are currently ineligible for the credit which is only available to those who are employed) along with several other important improvements. A complementary proposal expands child tax credits, which are among the most common and effective anti-poverty programs in use throughout the developed world and give cash to families with children in the form of a refundable tax credit.

Food insecurity and poor nutrition are among the most devastating effects of poverty, but nutrition assistance programs like SNAP have been proven to be effective. We Included the Closing the Meal Gap Act, which expands snap coverage and benefits, as well as the Weekends without hunger act, which provides support for meal programs on weekends, holidays, and the summer time, when school is out of session and many kids go without food.

Lastly, we include Barbara Lee’s Pathways out of Poverty Act, which is a sweeping set of reforms that expands Pell Grants, school lunch programs, unemployment insurance, housing assistance, and several other programs. The bill would also establish a Poverty Impact Division at the congressional budget office for assessing the effects of legislation on poverty, and would establish an Interagency poverty working group at the department of health and human services.

Expand Social Security: 170 cosponsors

Pathways Out of Poverty Act: 24 cosponsors

Child Tax Credit Expansion: 112 cosponsors

GAIN Act: 55 Cosponsors

Modernize the EITC: 18 cosponsors

Expand SNAP: 115 Cosponsors

Weekend School Lunches: 28 cosponsors

Progressive Taxation

Since the 2008 financial crisis, Americans have become more attuned to the problem of extreme income and wealth inequality. Extreme inequality entrenches the wealthy in positions of power, threatens to undermine democracy, and even slows economic growth. In one of the most influential books on inequality, French economist Thomas Piketty showed that there is a tendency for the rate of returns on investments to be higher than the growth of the economy overall. That means that you can typically make a lot more money simply by owning capital than you can by working for a living (we’ll discuss Piketty and inequality more in the section on Labor). This is a recipe for disastrous inequality, and since the wealthy overwhelmingly get their income from returns on capital as opposed to compensation for labor, and can’t be ignored when designing tax policy.

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The wildly popular “Buffet Rule,” or Millionaires Tax, would help slow the rise of inequality by requiring everyone with an income of one million or more be subject to an effective tax rate of 30%. Since millionaires primarily receive income from returns on capital, and returns on capital are subjected to lower rates than taxes on wages, many millionaires wind up paying significantly less than 30%.

We also include a bill that closes many of the loopholes that allow wealthy individuals and profitable corporations to avoid paying their taxes.

Close Individual and Corporate Tax Loopholes: 59

Millionaire’s Tax: 9 cosponsors

Criminal Justice and Policing Reform

The United States imprisons more people per capita than the Soviet Union did at the peak of it’s gulag period. Police in the United States kill citizens at a much higher rate than similar countries, and persistent structural racism leads to these outcomes disproportionately affecting people of color. While many elected Democrats have been slow to take on these issues, several have proposed important reforms.

The cash bail system is abusive and penalizes the poor for not having money. Data for Progress recently polled ending this system and found that it has strong net support. Congressional Democrats have introduced legislation to this effect, and Senator Kamala Harris makes a very compelling case for ending cash bail here.

Mandatory Minimum Sentencing laws set harsh minimum prison sentences for a number of different offenses, most being drug offenses. Mandatory miminums have increased the number of incarcerated people and have deepened racial disparities in incarceration, but provide no discernable benefits.

We combined three bills for marijuana decriminalization/legalization. The Ending Federal Marijuana Prohibition act would remove all criminal penalties for possession of marijuana and gives transfers the authority to regulate marijuana from the Drug Enforcement Administration to the Bureau of Alcohol Tobacco, Firearms and Explosives. The Regulate Marijuana Like Alcohol Act is a similar bill, and the REFER act prohibits the use of federal funds in marijuana enforcement in states and municipalities which have decriminalized it.

In 2014, Eric Garner was killed by a police officer who held him in a chokehold. Despite a video recording the killing, the officer involved was not indicted. Hakeem Jeffries’ Excessive Use of Force Prevention Act forbids police from using chokeholds.

Legalize Marijuana: 44 cosponsors

End Cash Bail: 38 cosponsors

End Mandatory Minimums: 9 cosponsors

Outlaw Chokeholds: 17 cosponsors


The overwhelming majority of people receive their income from wages earned by working, pensions (deferred wages earned by working), and social insurance (government benefits earned by...wait for it... working). Ensuring that workers get their fair share of the national income should be a top priority for any progressive party. Piketty has noted the role of collective bargaining, minimum wage laws, and alternate forms of corporate governance and ownership in combating inequality by boosting workers’ bargaining power. This is sometimes called income predistribution (as opposed to redistribution), or ensuring that the rich don’t take more than their fair share. Ensuring a fair distribution of wealth is not the only reason for Democrats to support pro labor policies, which also help prevent discrimination and abuse -- and can even help Democrats at the ballot box.

Unions have been in decline in the United States for decades, and only 10.7% of all workers are currently union members. As unions have declined, income inequality has grown while wages for the working class have stagnated. This has not happened by accident but is the result of a concerted attack on workers through legislation and court cases at both the state and federal level. The recent Janus decision struck a major blow and there is more coming down the pike.

The legislation we’ve included here tackles multiple labor-related issues. Legislation to expand collective bargaining and require codetermination would strengthen the voice of workers. Codetermination, which has majority support, would require worker representation in corporate boards of directors. This would push corporations to be responsive to a broader range of stakeholders than just stockholders looking for the biggest short-term return.  

We’ve also included several pieces of legislation aimed at directly tackling income inequality: minimum wage increases, wage theft prevention, and a job guarantee pilot. Wage theft takes billions from the pockets of workers across the US and affects all types of workers. The wage theft prevention legislation here would put a major dent in this by instituting proactive safe guards for America’s workers.

Our final group of legislation tackles some of the more coercive aspects of the current labor market: non-compete clauses and forced arbitration. Both of these practices give even more strength to companies. Forced arbitration in particular has been used to protect sexual harassers, allowing them to harass workers for decades.

Minimum Wage: 169 cosponsors

Wage theft prevention: 24 cosponsors

Non-compete ban: 8 cosponsors

Expand collective bargaining: 61 cosponsors

Codetermination: 7 cosponsors

Job Guarantee Pilot: 35 cosponsors

Forced Arbitration Ban: 58 cosponsors

Pro-Democracy and Anti-Corruption

The United States system of government was designed to be highly undemocratic. The Senate gives enormous disproportionate power to small states inhabited by populations that are older, whiter, and more rural than the country as a whole. Gerrymandering is used aggressively in several states to gain partisan advantage, and many more states use voting restrictions (often from the Jim Crow era) to limit the franchise.

Some pro-democracy reforms would probably benefit Democrats electorally, but ultimately, creating a fairer system of government should be pursued because it is a good in and of itself. Our analysis includes cosponsorship of pro-democracy reforms in the 115th Congress, but Democrats are signaling that this will be an especially high priority in the 116th Congress. The first bill Democrats introduced in the new session was a sweeping set of pro-democracy reforms, and DC representative Eleanor Holmes Norton has announced that her bill admitting DC as a state has more initial cosponsors than any of her previous attempts.

We polled statehood for DC and automatic voter registration as a part of our New Progressive Agenda Project and found both to be popular. Establishing Election Day as a holiday would make it easier for working people to participate in elections. We also included John Lewis’s Voter Empowerment Act, which establishes several federal level requirements that limit state governments’ power to disenfranchise their own citizens. Along similar lines, we included a proposal for an amendment to the Constitution establishing voting as an affirmative right.

At present, there are very few rules in place that prevent conflicts of interest in the lobbying industry. Senator Warren has introduced a bill which would drastically reduce the influence of lobbyists and eliminate those conflicts. Her bill would ban all members of Congress from receiving donations from lobbyists or lobbying firms, bar former members of congress and agency heads from becoming lobbyists once out of office, prohibit members of Congress and other elected officials from owning and trading individual stock, increase disclosure requirements, and several more. The bill has an impressive list of endorsements including the AFL-CIO and several government transparency advocacy organizations, but only has 9 house cosponsors.

DC Statehood: 175 cosponsors

Automatic Voter Registration: 63 cosponsors

Limit lobbying: 9 cosponsors

Election Day Holiday: 31 cosponsors

Constitutional right to vote: 36 cosponsors

State level voting standards: 179 cosponsors

Reproductive Rights

With the appointment of Brett Kavanaugh to the Supreme Court in 2017, reproductive health advocates have been warning that women’s access to safe and legal abortions could be threatened. However, access to safe and legal abortions have been under threat for several years now. Analysis shows that since 2011, states have adopted hundreds of abortion restrictions such as mandatory counseling or waiting periods.

These restrictions are largely clustered in states with conservative legislatures, meaning that women’s access to reproductive health care varies across the United States. According to the Guttmacher Institute, 29 states are considered hostile or extremely hostile to abortion rights. Moreover, these restrictions are more likely to affect poor women of color and women in rural communities, while wealthy women generally maintain legal abortion access. The Women’s Health Protection Act is a federal bill that would prevent these state by state restrictions that have characterized the attack on reproductive rights over the last several years. Originally proposed in 2013, it has been reintroduced by Tammy Baldwin in the Senate along with Marcia Fudge and Lois Frankel in the House of Representatives.

The Hyde Amendment, which was passed in 1976, is another barrier to widespread access to safe and legal abortions. Hyde blocks federal Medicaid funding for abortion services, with the exception of pregnancy by rape or incest, or when the life of the mother is endangered by continuing the pregnancy. This law disproportionately affects poor women of color, who are the majority of Medicaid enrollees. Congressional Republicans have also recently proposed twenty-week bans, despite widespread unpopularity.

Repeal the Hyde Amendment: 135 cosponsors

Limit state level abortion restrictions: 168 cosponsors

Require state department to restore reporting on reproductive rights: 55 cosponsors

20 Week abortion ban: 3 members voted for the ban


The higher education system in the US has put an enormous burden of debt on those who have sought a college degree. While not all Democrats are on board yet, publicly financed tuition free college is a popular and much more sensible system. We include Pramila Jayapal’s College for All Act which makes college tuition free, in addition to a more moderate bill which expands tax credits for full time students.

College is only one part of the US education system, and universal Pre-Kindergarten is another important program which would have many long term benefits, especially for underserved kids. Vocational training is another important area, since college is not appropriate for everyone and should not be the only path to the middle class. For example, the German apprenticeship program has been very successful and advocates in the US point to several potential benefits of fully funded jobs development programs that work directly with labor organizations.

Tuition free college: 47 cosponsors

Universal Pre-K: 5 cosponsors

Increase student tax credits: 113 cosponsors


The recent IPCC report was nothing short of dire, warning of severe environmental, humanitarian, and economic catastrophe if greenhouse gas emissions are not cut in half in about 12 years time. At the same time, the Trump administration has been rolling back EPA regulations and emissions standards. Most of the policies we included for the environment are fairly limited in scope, but even so do not garner as much support from house Democrats.

The Keep it in the Ground Act would halt the granting of new leases for fossil fuel extraction on federal lands, and halt the granting of permits for offshore drilling. For renewable energy transitions, we combined the 100 by 50 Act and the OFF Act. We also include the CLEANER Act, which closes several loopholes and exemptions that allow polluters to skirt EPA regulations.

Hydraulic fracture, or fracking, is a controversial method for fossil fuel extraction that many environmental activist believe should be banned. Since fracking poses a risk of groundwater contamination, some Democrats in Congress have proposed laws that would require groundwater testing at fracking sites to be made public, and that the chemicals injected into the ground be disclosed to regulators. At present, many potential groundwater contaminants are not disclosed to the public since companies argue that they are proprietary, despite being a public health risk.

Lastly, we include a House resolution introduced by Republicans expressing that a carbon tax would be detrimental to the US economy. Since activists from the Sunrise Movement and Representative-Elect Alexandria Ocasio Cortez have led the push for a Green New Deal, some on the right have offered rhetorical support for a carbon tax. A carbon tax by itself is not sufficient to eliminate greenhouse gas emissions, but we included the vote here as representative of a minimal commitment to dealing with the climate crisis.

Stop new offshore drilling: 25 Cosponsors

Renewable energy: 59 cosponsors

Close EPA loopholes: 72 cosponsors

Fracking Chemicals Disclosure: 66 cosponsors

Require Fracking Groundwater testing: 36 cosponsors

Resolution Expressing that a carbon tax would be economically detrimental: 7 members voted for the resolution


Americans are nearly unanimous in the view that there should be more regulation of the financial sector, although even among Democrats this tends to be low on the list of issue priorities. Congressional Democrats have proposed new regulations on Wall Street in addition to a financial transaction tax, which would discourage high volume trading and speculation while leaving ordinary investors unaffected.

Very few Democrats advocate for public alternatives to private finance, but Senator Gillibrand’s Postal Act would allow the Post Office to offer checking accounts and other basic financial services. This would provide relief to millions of Americans who are unbanked or underbanked, who are forced to turn to alternative, and often predatory, financial products to carry out everyday transactions.

Republicans (and a few Democrats) passed a bill which rolls back several of the regulations that were established in the Dodd-Frank bill, which passed in the wake of the 2008 financial meltdown. We included this roll call vote as well.

Financial Transaction Tax: 37 cosponsors

Wall street regulation: 55 cosponsors

Postal Banking: 17 cosponsors

Dodd Frank Rollbacks: 33 members voted yes

Family and Child Development

Strong majorities of Democrats in the 115th Congress cosponsored Senator Gillibrand’s Family Leave Act (she makes the case for it here), and the Child Care for Working Families act, which improves affordability and quality of childcare for low and middle income families. Paid family leave and affordable childcare would provide relief to families who balance caregiving and working. Allowing parents to spend more time with their children is crucial for early childhood development, and family leave and affordable child care would also help firms retain talented employees by making the work life balance more manageable. There is also evidence to suggest that family leave policies increase labor force participation for women.

Affordable Child Care: 138 cosponsors

Paid Family Leave: 156 cosponsors


One (positive) consequence of polarization is that the Democratic Party has, on the whole, moved to the left on immigration and is now relatively united in opposition to Donald Trump on the issue. There is broad support for a pathway to citizenship -- though divisions remain regarding what precisely this will entail. The movement to Abolish Immigration and Customs Enforcement is growing and while the median Democratic representative may not endorse such a move, there are few Democrats left who are willing to go on record defending the agency.

In May 2018, Senator Kamala Harris and Representative Pramila Jayapal introduced the Detention Oversight Not Expansion (DONE) Act. This legislation had two main provisions. First, a moratorium would be placed on the construction of new ICE detention facilities. Second, funding for bodies that oversee ICE would have been increased, allowing for human rights violations to be better investigated and made public.

In June 2017, Rep. Bob Goodlatte (R-VA-6) introduced H.R.3003, the No Sanctuary for Criminals Act. The legislation would have amended the Immigration and Nationality Act that would have required federal, state, local or individual from complying with federal immigration law and prohibited non-collaboration regarding enforcement. This legislation would have, in effect, elimited the legal basis for “Sanctuary Cities,” or municipal governments that limit their collaboration with the federal government regarding the enforcement of immigration law.

After the movement to abolish ICE garnered traction, the right introduced legislation to praise ICE. In July 2018, Rep. Clay Higgins (R-LA-3) introduced H.Res.990, the Supporting the Officers and Personnel who Carry out the Important Mission of the United States Immigration and Customs Enforcement. The purpose of the resolution was to “Expresses support for U.S. Immigration and Customs Enforcement (ICE) officers and personnel and denounces calls for ICE's abolishment.” Nearly all Democrats rejected the gambit, voting present

Democrats also largely support a path to citizenship for undocumented migrants living in the United States, specifically those who are part of the Deferred Action for Childhood Arrivals program. A bipartisan Senate bill sponsored by Senators Chris Coons (D-DE) and John McCain (R-AZ) would have provided a pathway to citizenship for 1.8 million people brought to the United States as children, paired with a study as to what measures may be needed to beef up border security. This bill carried the support of every Democrat (and Democrat-aligned independent) in the chamber except for Senator Joe Manchin (D-WV).

Oversight for migrant detention facilities: 118 cosponsors

Punish Sanctuary Cities: 187 members voting no

Resolution supporting ICE: 167 members voting no or present

Path to Citizenship: 165 members supporting

Gun Control

Gun control is one of the top priorities for the Democratic base, and mass shootings have sparked a new wave of activism on the issue. Democrats in Congress are highly unified on gun control, with the overwhelming majority cosponsoring legislation to ban assault rifles. Very few Democrats broke ranks to vote for the Concealed Carry Reciprocity Act, which requires that all states recognize concealed carry permits granted to gun owners by any other state.

Assault weapons ban: 175 cosponsors

Concealed carry reciprocity: 6 members voted yes

Health Care

In 2018, Democratic primaries across the country featured candidates endorsing Medicare for All, leading political commentators to acknowledge a decidedly leftward shift on this issue in the Democratic Party. In midterm races, about half of the Democratic nominees voiced their support for Medicare for All. Although the Affordable Care Act was passed under duress, since 2010 the ACA, and various provisions in particular, have grown in popularity. Increased support for the ACA and a push for Medicare for All comes at a time when Americans are enduring growing healthcare costs.

According to a Kaiser Health tracking poll from March, more than half of Americans think that lowering the cost of prescription drugs should be a top priority in Washington. Of all the issues polled by Kaiser, the cost of prescription drugs topped the list in terms of importance. Cutting the cost of prescription drugs would dramatically decrease the cost of healthcare in the United States, and their is recourse for this action to be taken by the U.S. Congress. However, a powerful prescription drug lobby is working to prevent these efforts.

According to the same Kaiser poll, 60 percent of respondents favor Medicare for All, including a majority of both Democrats and Independents, and about one-third of Republicans. Medicare for All would eliminate the private healthcare insurance industry, and extend coverage to millions of uninsured Americans. Medicare for All would also likely reduce profits for prescription drug companies. Given the growing support for Medicare for All amongst the U.S. public, and the dearth of candidates elected who ran on this issue, the Medicare for All bill seems ripe for success.

However, there has been a showing of support for bills that reverse efforts to extend medical coverage more broadly. For example the Verify First Act, which makes access to affordable healthcare more difficult for people in need, passed the House in 2017.

Medicare for All: 121 cosponsors

Rx reimportation and cost caps: 39 cosponsors

Verify first act: 8 members voted yes


Housing is an under-discussed issue in the US. Increased rents squeeze families and eat away at wage growth, but the problem is multifaceted, and requires a comprehensive solution. We polled expanded public housing investments as a part of our New Progressive Agenda Project, and found that it has net positive support in about half of congressional districts around the country. Bills that expand public housing investments have been introduced by Senator Booker (he makes the case for his bill in the New Progressive Agenda Project)  and Senator Warren. Senator Warren also introduced a bill which establishes new housing nondiscrimination laws, which define sexual orientation and gender identity as protected classes.

Housing Nondiscrimination laws: 85 cosponsors

Public Housing investments: combined 6 cosponsors


Safe and functional infrastructure is crucial, and neglecting infrastructure is astoundingly costly. We included a house resolution “Supporting efforts to enact a bold jobs and infrastructure package that benefits all Americans, not just billionaires.”

Infrastructure investments: 154 cosponsors

Silly Bullshit

One of the most significant powers the federal government has is the ability to sustain large levels of debt to finance spending for the public benefit. However, many conservatives believe government’s only role is to enforce property rights, and by extension believe that social spending should be cut. While the empirical and logical basis for the benefits of austerity are trash, it persists as central part of conservative ideology. Since middle class tax hikes and cuts to social spending tend to be extremely unpopular, far right billionaires such as the Koch brothers usually need to resort to underhanded tactics to implement them. A balanced budget amendment, while it may sound innocent, would amend to constitution to require that the federal budget be balanced every year, forcing spending cuts and tax hikes.

Balanced budget amendment: 7 members voted for the amendment.

The Nitty Gritty

This section goes into the details of the model itself. Let \(V_{ij}\) be a binary variable which encodes whether or not the member in district \(i\) supports issue \(j\). We assign a Bernoulli distribution to this variable, which is a function of a linear predictor as follows $$V_{ij} \sim \mathbf{Bernoulli}(p_{ij})$$ $$p_{ij} = \mathbf{logistic}(x_i\beta_j)$$ Where \(x_i\) is the vector of district predictors for district \(i\), and \(\beta_j\) is a vector of regression coefficients for issue \(j\). The coefficient vector \(\beta_j\) is drawn from a multivariate normal distribution with mean vector \(\mu_j\) and covarinace matrix \(\Sigma\). $$\beta_j = \mathbf{MultivariateNormal}(\mu_j,\Sigma)$$ To account for different patterns in behavior on votes vs cosponsorships, we model the components of the mean vector with a dummy variable for whether or not the issue was voted on, i.e. $$\mu_j = \gamma_0+\gamma*isVote_j$$ Where the coefficients here are assigned weakly informative priors. We construct the covariance matrix from a diagonal scale matrix \(\mathbf{\tau}\) and a correlation matrix \(\Omega\) so that $$\Sigma_{ij} = \tau_{kp}\Omega_{pq}\tau_{ql}$$ Weak priors are assigned to the scale matrix $$\tau_{kp}\sim\mathbf{HalfCauchy}(5), \ if \ k = p$$ $$\tau_{kp} = 0, \ if\ k \ne p$$ and the correlation matrix is drawn from an LKJ correlation distribution $$\Omega \sim \mathbf{LKJCorr}(2)$$ This is implemented with a non-centered parameterization for more efficient sampling, which involves expressing \(\beta_j\) in the following equivalent form $$\delta_j \sim \mathbf{Normal}(0,1)$$ $$\beta_j=\mu_j+L\delta_j$$ Where \(L\) is the lower triangular matrix resulting from the Cholesky decomposition of \(\Sigma\)