"What worries me the most," said Biden, is the "almost drumbeat of denigration of the institutional structures that govern us." He added, "when you delegitimize the courts, you delegitimize the legislative body. It's corrosive. and it it makes it impossible to reach compromise."
Biden, who in addition being vice president under President Obama for eight years was Delaware's longest-serving Senator, said that when Americans lose faith in the law or the courts, "things begin to crack."
He said he was "saddened" to feel compelled to defend the free press while standing at the Newseum, a museum dedicated to the press and the First Amendment.
"To question the actual legitimacy of a free press is one of the most dangerous things out there. The degree that we depart and denigrate our institutions and the fourth estate, I think we really, honest to god, honest to god, weaken our ability for self-government," said Biden. "We undermine it and become weaker and not stronger."
In a tweet last month, Trump called the media the "enemy of the American people."
The former vice president said that while he has certainly been on the bad end of press coverage, unencumbered journalism was nonetheless indispensable to democracy.
"I have taken my fair share of hits from the press, being covered by the very best and some of the worst. Some of you press guys are lousy just like some senators are lousy, doctors are lousy, lawyers are lousy. But it doesn't matter," he said. "We should never challenge the basic truth that an independent and free press is the fundamental element in functions of our democracy."
Biden went on to quote former head of United States Special Operations Command Ret. Adm. William McRaven -- calling him "a true patriot" and not a "left-leaning liberal" -- who said in a statement last week that calling the media the enemy "may be the greatest threat to democracy in my lifetime."
The day after Trump's address to a joint session of Congress, Biden called the president's words "much more presidential in tone" than before. "There was talk of bipartisanship," added Biden. "But as the old saying goes, the proof of the pudding is in the eating."
Biden accepted the award from Republican former Sen. Bob Dole of Kansas and Democratic former Sen. George Mitchell of Maine.
"We can be Democrats, Republicans or independents and protesters," said Dole. "Americans are patriots, and we have had a patriot serving as vice president for eight years. And he has made us proud. Whether you are Democrat or Republican, Joe Biden makes you proud."
Dole joked that he got a call from Trump before he left for the event. "He said don't say too many good things about Biden. He may run against me later on."
Sen. Chris Coons (D-Delaware), Sen. Pat Toomey (R-Pennsylvania), Rep. Will Hurd (R-Texas) and Rep. Kyrsten Sinema (D-Arizona) also received the inaugural Legislative Action Awards.