Last week, Paul Manafort signed a cooperation agreement with special counsel Robert Mueller and pleaded guilty to charges that included conspiracy related to his lobbying on behalf of a pro-Russian Ukrainian political party without registering with the United States government. One fascinating and underexplored thread that has emerged from the agreement is the apparent role his attorneys from Skadden, Arps, Slate, Meagher & Flom LLP played in aiding his criminal conspiracy. CNN reported on Friday that Mueller had referred an investigation into work done by Skadden lawyers—including Greg Craig, who served as White House counsel under President Barack Obama—to the U.S. Attorney’s Office for the Southern District of New York.

We don’t have all the information, so it’s hard to say whether Skadden lawyers broke the law when they wrote a nominally “independent” report on behalf of Manafort and Ukraine President Viktor Yanukovych that was allegedly cooked up to justify the prosecution of the politician’s chief rival. It seems clear that at the very least they violated their ethical obligations. Many lawyers, who have hung out at the edges of national scandals and given legal advice and cover to those who were ultimately held responsible, have escaped punishment for their acts. It is critical in this case for prosecutors and state bar regulators to break with this tradition and hold the lawyers involved to a higher standard: Manafort’s attorneys must face consequences for any unethical or unlawful actions.

Even if Manafort’s attorneys were not directly involved in the lobbying work, they might still have criminal liability.

The description of the charges to which Manafort pleaded guilty on Friday gives clues about the Skadden lawyers’ role. At the request of Manafort, the law firm prepared a report supporting the Ukrainian government’s criminal prosecution of Yanukovych’s political adversary, Yulia Tymoshenko. The charges against Manafort show that he planned to use the Skadden report in a sustained lobbying effort on behalf of the Ukrainian government. Specifically, he circulated the law firm’s report in an effort to defend the prosecution of Tymoshenko as fair and deserved rather than as a politically motivated way for Yanukovych to rid himself of a powerful adversary.

These lawyers could be charged criminally under Title 22, Section 612 of the U.S. Code for failing to register as foreign agents. There is an exception to the registration requirement for lawyers who provide legal representation to foreign countries, but the exception does not apply if the law firm is engaged in lobbying work. It is not clear, though, how much of a role the Skadden lawyers played in the lobbying effort itself. If they were directly involved, they may have violated the law.

Even if Manafort’s attorneys were not directly involved in the lobbying work, they might still have criminal liability. If any Skadden lawyers were aware that their work was being used in this way, as part of an illegal effort to lobby the government on behalf of a foreign principal without registering, they may have knowingly assisted in a criminal act, which is itself a crime.

The D.C. Bar has a code of conduct stating clearly that it is unethical to commit a crime and similarly problematic to assist a client in doing so. If the lawyers violated the foreign agent registration law or knowingly assisted Manafort in doing so, local regulators could strip them of their law licenses and fine them as a result. Disciplinary authorities at the relevant local bar can do this even if prosecutors decline to pursue the charges.

The lawyers at Skadden likely violated other ethical requirements as well. The charges against Manafort make it clear that the lawyers knew that Ukraine’s criminal charges against Tymoshenko were not supported by evidence. Manafort’s sworn statement says that he was “told privately in writing by the law firm that the evidence of Tymoshenko’s criminal intent ‘is virtually non-existent’ and that it was unclear even among legal experts that Tymoshenko lacked power to engage in the conduct central to the Ukraine criminal case.” These lawyers prepared a report concluding otherwise anyway. This could violate professional conduct rules requiring honesty, competence, and independence.

The charges against Manafort also reveal that the law firm was retained to represent not only Manafort but also Ukraine, and to provide support and training to Ukrainian prosecutors assigned to the case. If, as the criminal information filing laying out the charges states, the lawyers knew that this was a questionable prosecution of an innocent person, motivated by political expediency rather than justice, their support is problematic as well. The lawyers may have violated local ethical rules barring conduct that interferes with the administration of justice. Disciplinary authorities rarely use this rule to punish lawyers, but few cases are as egregious as knowingly helping a political actor prosecute an innocent person.

We also know that the law firm was paid more than $4 million for the report, an exorbitant sum even for the most elite lawyers. Manafort funneled the money to the firm through an offshore account so as to avoid disclosing the payment, and the Ukrainian government falsely reported the cost of the report as $12,000. This conduct could constitute money laundering under federal law. It’s hard to build a criminal case on the assumption that lawyers should have been more diligent in identifying the source of funds paid to them, or that they intentionally avoided finding out information about the source of the payment and the way the client used their work. But the federal system does allow prosecutions for certain crimes where the perpetrators remained willfully ignorant of the scope of their conduct, and this may be one of those cases.

All of that said, lawyers often escape the consequences of their advice. The lawyers who helped Enron engage in accounting fraud were never charged or disciplined for their conduct. Likewise, the government lawyers who wrote the opinion justifying the torture of suspected terrorists in 2002 avoided professional sanction even though experts agree that their legal analysis was clearly wrong. So we shouldn’t be surprised if these lawyers avoid punishment too.

While unsurprising, this would be a grave mistake. It is becoming increasingly clear how important the rule of law is to democracy and how central a role lawyers play in upholding it. As we praise lawyers like Mueller and his team who are working to uphold the rule of law, we simultaneously need to hold those lawyers who violate their obligations responsible for their illicit actions.