Elizabeth Holtzman is a former member of Congress from New York who won national attention for her work on the House Judiciary Committee during Watergate. She was subsequently elected district attorney of King’s County—the borough of Brooklyn. This interview has been edited and condensed for clarity.

Listen to Elizabeth Holtzman on the Start Making Sense podcast.

Jon Wiener: We’ve worried for a long time that Trump could fire Special Counsel Robert Mueller, or he could pardon everyone being investigated by Mueller, which would end those investigations. But now Mueller has teamed up with the attorney general of New York State, Eric Schneiderman, on their investigation into Paul Manafort and his financial transactions. What is the significance of this cooperation?

Elizabeth Holtzman: Mueller is sending a strong signal to people who are subjects or targets of the investigation into possible collusion between the Trump campaign and Russia. The message is that the president can’t exonerate you just by a pardon, because the president’s power to pardon is limited to federal offenses. It does not cover state offenses. What Mueller is saying is, “Yes, Mr. Manafort, maybe President Trump will pardon you, but that’s not going to get you off the hook, because you can be prosecuted under state laws.”

JW: The feds can prosecute some crimes that state attorney generals can’t, of course—starting with crimes committed outside the State of New York. What else can Mueller investigate that New York State Attorney General Schneiderman cannot investigate?

EH: Mueller can investigate the firing of FBI Director James Comey, for example. That was a firing of a federal official, and an obstruction of justice. potentially. That’s something that Eric Schneiderman wouldn’t have the jurisdiction to investigate. On the other hand, it may be that Eric Schneiderman’s investigations into financial activities by Mr. Manafort could lay the basis for prosecution of Mr. Manafort on state charges, and that might be sufficient to get Mr. Manafort to talk to Mueller’s team about what he knows about the Trump campaign, Trump himself, and collusion with Russia. Even if the state charges, assuming there’s a basis for them, don’t relate to any federal offense, they could become a basis for putting pressure on Trump campaign officials to cooperate with federal law enforcement authorities.

JW: Trump’s lawyers have filed papers arguing that the president has the authority to hire and fire, and therefore, it could not be an obstruction of justice for Trump to fire Comey. You’re a former prosecutor, could that be correct?

EH: Trump’s intent is going to be critical in that matter. An obstruction of justice requires a corrupt intent, and if the purpose of the firing is to stop an investigation, then that corrupt intent may well exist and that may be a basis for the prosecution. In addition, and this is very important, even though the president may have the full authority to hire and fire anybody, if he’s doing it for the purpose of obstructing an investigation, that becomes an impeachable offense. Remember, one of the grounds for the impeachment of Richard Nixon, the vote for impeachment by the House Judiciary Committee, was Nixon’s firing—or causing the firing—of the special prosecutor, Archibald Cox, who was closing in on him and wanted White House tapes that could reveal whether Nixon himself was involved in the coverup. So yes, Mr. Nixon may have had full authority, constitutional authority, for that firing—I’m not conceding that, but let’s even assume he did; just note that that firing was nevertheless a basis for the vote for impeachment.

JW: You were a key member of the House Judiciary Committee when it drafted articles of impeachment against Nixon. The articles of Impeachment covered obstruction of justice, abuse of power, and contempt of congress. Do you have any advice or wisdom to offer to our current House Judiciary Committee?

EH: The House Judiciary Committee has a major responsibility to protect the country from the destruction of its democratic and constitutional system. The framers of the constitution created an impeachment process to protect our democracy. And that’s really what’s at stake now, when a president takes the law into his own hands and puts himself above the rule of law. We cannot have a president decide who is going to investigate him and whether or not he’s committed a crime. There is a rule of law, whether you’re president of the United States, or a beggar on the streets, there’s a rule of law that applies to everyone equally. The minute we abandon that, we’re on the way to dictatorship, fascism, and loss of our basic freedoms.

With Nixon, in the end the House Judiciary Committee voted articles of impeachment not because Congress said, “We’ve got to remove the president,” but because the American people said, “Enough’s enough. We’re not a Banana Republic, and the president can’t decide who’s going to prosecute him, and the president is not above the law.” That’s what forced Congress to act. You have to have egregious acts by a president. We have some very egregious acts here. And you have to have the American people saying, “This is not tolerable in a democracy.” The minute you have those two things, the House Judiciary Committee needs to act.

JW: What to you are the most important elements that could lead to impeachable offenses Trump has committed? Obviously, firing Comey looks like an obstruction of justice; beyond that, what’s at the top of your list of the most significant things that Trump has done to endanger our democracy?

EH: One example: misleading the American people about the nature of his son’s meeting with the Russians. Also, all the attacks on Attorney General Sessions: Were those attacks designed to get Sessions to resign and allow Trump to appoint a new attorney general who could remove Mueller? We don’t know that, but that needs to be looked at, because that could be grounds for a possible obstruction of justice charge in an impeachment. And the attacks on Mueller himself: Trump saying that the Russia investigation is a hoax, it’s fake news. This flies in the face of reality and is an attempt to undermine the investigation, which is not what a president should be doing. Mr. Trump is treading on very dangerous grounds by emulating Richard Nixon.