In a development described as "staggering" in the ongoing saga involving President Donald Trump and adult-film actress Stormy Daniels—and the efforts made to keep her silent about the sexual affair she claims they had—Trump's personal attorney Michael Cohen on Wednesday told a federal court judge that he will plead the Fifth Amendment in order to avoid self-incrimination if he is forced to testify in the case.

As the Washington Post reports:

Cohen's declaration, in support of his request to pause proceedings in the civil case, cited an "ongoing criminal investigation by the FBI and U.S. Attorney for the Southern District of New York." Earlier this month, the FBI raided Cohen’s home, office and a hotel room where he had been staying. That investigation includes looking into the effort to quash embarrassing stories about Trump during the 2016 campaign, according to a person familiar with the matter.

Appearing on MSNBC's "The Last Word w/ Lawrence O'Donnell" late Wednesday night, Michael Avenatti, the lawyer representing Daniel's (whose real name is Stephanie Clifford), said in response that Cohen invoking his Fifth Amendment rights was a "very big deal" and a "staggering development."

Michael Avenatti: "Michael Cohen is claiming he can't answer the questions because the answers will incriminate him. This is a staggering development. It cannot be over exaggerated. It cannot be overstated. This is a big deal." pic.twitter.com/iRDwFk2kHZ — Together we rise (@Matsamon) April 26, 2018

Of course, "taking the Fifth" is a constitutionally protected right and invoking it does not, in the eyes of the law, indicate guilt. However, not just a few people were pointing out Trump's repeated public statements on what doing so suggests:

Five Times Donald Trump Bashed Pleading The Fifth Trump’s past comments about pleading the Fifth look pretty ominous now Michael Cohen has now indicated that he intends to plead the Fifth Amendment SCROLL TO CONTINUE WITH CONTENT Never Miss a Beat. Get our best delivered to your inbox.





And 2016 Trump would suggest that makes Cohen guilty.#ThursdayThoughts pic.twitter.com/r7SHs0HY26 — PoliticsVideoChannel (@politvidchannel) April 26, 2018

However, at least to Avenatti and many others, the development is one that cannot be ignored.

"Never before in our nation's history has the attorney for the sitting President invoked the 5th Amend in connection with issues surrounding the President," Avenatti said in an earlier tweet. "It is esp. stunning seeing as MC served as the ‘fixer’ for Mr. Trump for over 10 yrs."

This is a stunning development. Never before in our nation’s history has the attorney for the sitting President invoked the 5th Amend in connection with issues surrounding the President. It is esp. stunning seeing as MC served as the “fixer” for Mr. Trump for over 10 yrs. #basta — Michael Avenatti (@MichaelAvenatti) April 25, 2018 “The mob takes the Fifth.” DT

And now their lawyers too apparently. Trump comments on Fifth Amendment resurface after Cohen filing https://t.co/9zD1HValiq — Richard W. Painter (@RWPUSA) April 26, 2018 Decision to take the Fifth Amendment by @realDonaldTrump lawyer Michael Cohen is powerful confirmation that the US Attorney's Office for SDNY was absolutely right in executing searches of Cohen under the crime-fraud exception to the attorney-client privilege. https://t.co/ikZfzSVPvw — Ted Lieu (@tedlieu) April 25, 2018

Watch Avenatti's complete interview with O'Donnell: