Ken Starr, the former independent counsel whose investigation resulted in the impeachment of President Bill Clinton, said Monday that, although the process reflects necessary checks and balances, lawmakers should be “careful” about going down that road.

“Impeachment is hell,” Starr said on “CBS This Morning” while promoting his new book, Contempt: A Memoir of the Clinton Investigation. He later added: “I think history is teaching us, the history of the ’90s is teaching us about 2018.”

The lawyer also said he sees “eerie similarities” between the Clinton investigation, which began as a probe into a real estate deal and turned into a case revolving around the president’s affair with an intern, and the ongoing efforts by special counsel Robert Mueller to look into Russian efforts to meddle in the 2016 election.

“You just don’t know what’s going to come before you,” Starr told host John Dickerson. “The key is, there are checks and balances to make sure that the prosecutor isn’t just doing anything and everything. The check at the time was for me to go to the attorney general and for the attorney general to go to the special division of the court and say, ‘This has to be investigated: The president of the United States may be committing crimes or perhaps has committed crimes.’ We’ve got to have a check and a balance. That’s what we have in the Mueller investigation.”

Impeachment chatter has gone relatively quiet in recent months as Democrats have tabled the issue ahead of November’s midterm elections, worried it could alienate voters. Trump, however, speculated about his own possible removal from office at a rally last week, telling his supporters that if he is impeached, “it’s your fault because you didn’t go out to vote.”

Starr said that, though Clinton was impeached in the House but acquitted in the Senate, the “system did work.”

“Our system of checks and balances worked; that is, the president was held accountable. He, in fact, had to answer to articles of impeachment,” Starr said. “But, at the same time, the American people are very forgiving, and we also want stability. And so, one of the messages of this book is, be careful about impeachment.”

He continued: “Impeachment is hell, and putting the nation through that process is really quite wrenching.”

Trump’s personal lawyers have been in a months-long tête-à-tête regarding Mueller’s request that the president sit down for a wide-ranging interview about his presidential campaign and any possible obstruction of justice. Starr said that he believes a U.S. president has an obligation to obey the law, but “if I’m a criminal defense lawyer, I’m saying, don’t do it.” Trump’s lawyers have worried that the president, known for making off-the-cuff remarks, would contradict himself and inadvertently lie to investigators.

“I don’t think he would engage in a perjury trap, no,” Starr said of the special counsel. “I have every confidence in Bob Mueller.”