It’s been over 30 years since Justice Clarence Thomas was confirmed to the Supreme Court seat once held by the great Thurgood Marshall, and it’s safe to say that his reputation for unethical behavior – which was poor to start with – has only gotten worse.

What are we supposed to think about a justice’s career that started with allegations of sexual harassment, moved on to extreme coziness with conservative political donors, then multiple instances of questionable gifts and payments to himself and his wife, and now revelations that years of free trips and perks lavished on him by right wing billionaire Harlan Crow went unreported—despite laws that clearly say they should be? Even after the news of Mr. Crow’s largesse first broke, it got worse: the billionaire had also bought Justice Thomas’ mother’s house in Savannah, Ga., a helpful real estate deal that Justice Thomas never reported, either.

We could think that Justice Thomas either doesn’t know or doesn’t care about the ethical standards expected of a Supreme Court justice, or the laws that apply to him as a public employee. But Clarence Thomas is a graduate of Yale Law School. Ignorance is not a believable defense here. So we have to conclude that Justice Thomas just doesn’t care about the rules, or thinks that he can ignore them.

That’s not the kind of person who belongs on the Supreme Court. If he wanted to do the decent and honorable thing, Justice Thomas would admit his wrongdoing and resign. Calls for him to resign are coming from pro-democracy groups, including the one I lead, top media outlets, and members of Congress.

But Justice Thomas doesn’t have a history of doing the decent and honorable thing. So that means others will have to hold him accountable. The question is how.

There are plenty of calls for impeachment, but with a Republican-controlled House the option would appear to be off the table. Meanwhile the Senate will hold hearings and may call Justice Thomas himself to testify. That is an important step. I would add that two other steps are absolutely essential right now: A Justice Department investigation and Supreme Court reform including an enforceable code of ethics.

The Justice Department has clear grounds to investigate Justice Thomas under a federal disclosure law that applies to government officials including Supreme Court justices. The law authorizes the DOJ to pursue both civil penalties and criminal fines from government officials who fail to report gifts as legally required.

Justice Thomas has claimed that the generosity he received from Harlan Crow was just “personal hospitality” – not subject to reporting. Even if some of that were true, some perks, like free use of Mr. Crow’s private jet for Justice Thomas’ personal travel, and the real estate transaction in Georgia are, according to most ethics experts, clearly in a different category.

The Justice Department can give a definitive answer as to whether Justice Thomas’ actions were not only unsavory, unethical, improper and all the rest – but also absolutely illegal. And it can call for imposition of a monetary fine. Even more important than the cash fine would be the impetus a finding of guilt would give to any effort to remove Justice Thomas.

And then, to help ensure that trust in the Court isn’t further eroded by scandal after scandal, we need to have Supreme Court reform. That means an enforceable code of ethics specifically for the Court, written to address the full range of ethical questions that could ever apply to justices’ behavior. In the longer term we should also have Supreme Court expansion, to counteract the far right capture of the Court that was achieved by totally unethical means. But that is a larger conversation.

It has been painful to watch Justice Thomas’corrupt behavior and its effect on the Supreme Court. We need judges on all our courts who understand the impact of their decisions on everyday Americans. Courts should be led by trustworthy, fair-minded judges who value equality and justice, uphold the Constitution, and protect civil and human rights for all Americans.

That’s not Clarence Thomas.

The writer is president of People For the American Way.