WASHINGTON — Michael Cohen, President Donald Trump’s longtime personal attorney, has joined a fairly short list of people who’ve been charged with lying to Congress — a club so exclusive in part because the crime can be very difficult to prove.

That's despite the fact that it isn't just a federal crime to lie to Congress while under oath — considered the “general perjury" statute — it’s also illegal to make false statements to Congress even if you're not under oath.

Cohen pleaded guilty Thursday to a single count of making false statements to the Senate Intelligence Committee during a closed-door meeting in 2017 about Trump’s plan to build a Trump Tower in Moscow.

During a court appearance in Manhattan Thursday, Cohen admitted that he lied several times to the congressional panel about project details, such as when it ended, whether he had agreed to travel to Russia for it and whether he had encouraged Trump to travel there as well.

It isn't that lawmakers don't accuse people of lying to or misleading Congress — that actually happens with some regularity. It's just that actual legal consequences rarely follow.

Here are a few people who’ve been found to have lied to Congress over the past half century or so, and what happened to them:

W. Samuel Patten

Under a plea agreement in late August, Patten, an American, Washington-based lobbyist, pleaded guilty to failing to register as a foreign lobbyist. The agreement revealed that in January, he “gave false and misleading testimony” — which included misinformation about his representation of a foreign government in the U.S. — to the Senate Intelligence Committee in its Russia probe. According to the agreement, after the interview with the panel, "Patten deleted documents pertinent to his relationships with the above-described foreign principals.” Under the agreement, Patten was not charged with making false statements.

W. Samuel Patten leaves the federal court in Washington on Aug. 31, 2018. Patten entered a guilty plea in federal court in Washington, shortly after prosecutors released a four-page charging document that accused him of performing lobbying and consulting work in the United States and Ukraine but failing to register as a foreign agent as required by the Justice Department. Jose Luis Magana / AP

Patten has not been sentenced for not registering as a foreign agent and had agreed to cooperate with Special Counsel Robert Mueller and federal prosecutors.

Roger Clemens

Clemens, a seven-time winner of the Cy Young Award as a Major League Baseball pitcher for teams such as the New York Yankees and Red Sox, was indicted by a federal grand jury in 2010 for making false statements and perjury during his 2008 testimony before the House Oversight and Government Reform Committee, when he claimed that he never used performance-enhancing drugs such as human growth hormone or steroids.

At the time, he faced a maximum of 30 years in prison and a $1.5 million fine, if convicted.

In 2011, an initial trial involving Clemens ended in a mistrial. The following year, he was acquitted of all charges.

H.R. Haldeman

Haldeman, who served as President Richard Nixon’s first White House chief of staff, was convicted, along with John Mitchell, one of Nixon's attorneys general, in 1975 of conspiracy, obstruction of justice and perjury related to testimony he gave to the Senate Watergate Committee investigating the cover-up of the Watergate break-in at the Democratic National Committee’s headquarters.

H.R. Haldeman, a former top aide to President Richard Nixon, testifies before the Senate Watergate Committee in Washington on July 31,1973. AP file

Haldeman was sentenced to a maximum of 8 years in prison, which was later reduced to one to four years. He wound up serving 18 months. Mitchell served 19 months in prison.

Harvey Matusow

Matusow, an ex-Communist who had become an FBI informant, was convicted of lying to Congress in the 1950s after revealing in his book “False Lies,” that in testimony to lawmakers, he had falsely named 200 people as Communists or Communist sympathizers just a few years earlier.

He faced the prospect of a maximum sentence of 25 years in prison and a $10,000 fine, but was ultimately sentenced to five years, of which he served 44 months.

Caspar Weinberger

Weinberger, a former Defense secretary, was indicted on felony charges in 1992 for lying to Congress about his role in the Iran-Contra scandal during the Reagan administration, in which officials sold arms to the Iranian government to support militant rebels in Nicaragua. Weinberger was among a number of Reagan aides who were charged with lying to Congress, along with Clair George, deputy director of operations at the CIA, and John Poindexter, Reagan's national security adviser.

Secretary of Defense Caspar Weinberger in Washington, D.C. in Feb. 1981. Bob Daugherty / AP file

Weinberger had been scheduled to stand trial, but before that occurred, President George H.W. Bush granted him and five other advisers involved in the scandal — including George — full pardons. Meanwhile, an appeals court reversed Poindexter's conviction.