A coalition of 90 left-of-center groups Monday called on lawmakers to hold formal hearings and investigate Supreme Court ethics and recent scandals involving its justices.

In a letter sent to party leadership on Capitol Hill and leaders of the Senate Judiciary Committee, the newly formed United for Democracy coalition said the court has “exempted itself from the most basic oversight.”

“In the wake of recent revelations of egregious impropriety by justices and this latest disastrous Supreme Court term, Congress must step up to conduct robust investigations and coordinated formal hearings into corruption, dark money, and interest-driven judicial activism at the Supreme Court in order to inform legislative action to bring true transparency and accountability to this broken Court,” the letter states.

The letter does not name any particular justice, but it follows a series of ProPublica investigations into undisclosed trips that Justices Clarence Thomas and Samuel Alito accepted from billionaires and major Republican donors. The justices have denied any wrongdoing.

In the wake of the reports, Senate Judiciary Committee Chairman Dick Durbin (D-Ill.) announced plans to mark up a Supreme Court ethics bill as Congress returns from the July Fourth recess, and Senate Majority Leader Chuck Schumer (D-N.Y.) on Sunday said Democrats will “explore every option” to address Supreme Court ethics.  

The letter — signed by groups including NARAL Pro-Choice America, several labor unions, End Citizens United and League of Conservation Voters — calls for a broad oversight effort that spans multiple committees.

“A coordinated multi-committee oversight effort would further Congress’s important legislative responsibilities with respect to the federal courts,” the letter, first reported by Politico Playbook, states.

“It would also enable accountability for any specific instances of lawbreaking and corruption by judges and their financial backers, expose the methods and mechanisms used by elite actors to secure undue influence over the judicial process, and educate the American people about the corruption and ethics issues as well as judicial policymaking and its devastating impact on our freedoms and families,” the letter continued.

Democrats have renewed calls for the Supreme Court to adopt a binding code of ethics in the wake of the recent ethics controversies, but the push has become deeply partisan. Republican lawmakers have portrayed the effort as an attempt to tear down the court’s 6-3 conservative majority.

There are also divisions among Democrats about how far to push Supreme Court reform on questions such as expanding the court or imposing term limits on justices.

“Congress not only has the power, but a sworn constitutional duty, to bring transparency and accountability to a Supreme Court that has been captured by wealthy and well-connected  special interests and to ensure equal justice under the law,” the letter states.