A contentious hearing on Capitol Hill on Tuesday touched on the two topics that may define the 2024 U.S. presidential election: Joe Biden's memory, and Donald Trump's alleged crimes.

Lawmakers heard from a former special counsel, Robert Hur, who investigated whether President Biden broke the law when classified documents from his time as vice president were discovered at his home.

HUR: "My task was to determine whether the president retained or disclosed national defense information willfully...I could not make that determination without assessing the president's state of mind. For that reason, I had to consider the president's memory..."

Hur declined to charge Biden, but ignited controversy when his report characterized Biden as a "elderly man with a poor memory."

That remark was siezed on by Republicans to assert Biden was unfit to serve, and met with fierce pushback from the White House and Democratic lawmakers.

Here's California Democrat Adam Schiff:

"You could have written your report with his comments about his specific recollection as to documents or a set of documents. But you chose a general pejorative reference to the president. You understood. You made that decision, didn't you, Mr. Hur, that you would ignite a political firestorm with that language, didn't you?"

Hur said that Biden's memory and state of mind were relevant to his conclusions about whether Biden knowingly retained sensitive information.

"I did not sanitize my explanation. Nor did I disparage the President unfairly. I explained to the Attorney General my decision and the reasons for it. That's what I was required to do."

The question of Biden's handling of sensitive documents contrasts with the criminal charges brought against the presumptive Republican nominee, Donald Trump.

Another special counsel accused the Republican of illegally retaining top secret national security information after leaving office and misleading investigators trying to retrieve it.

Hur's report cited distinctions between the two cases, including alleged acts of obstruction by Trump.

But Republican lawmakers accused the Justice Department of a double standard.

Representative Tom McClintock:

"The foundation of our justice system is equal justice under law. That's what gives the law its respect and its legitimacy...You destroy this foundation and the rule of law becomes a sick mockery. It becomes a weapon to wield against political rivals and a tool of despotism."

Hur was appointed as a U.S. attorney by Trump and made special counsel by Biden's Attorney General Merrick Garland after Biden's documents surfaced.

According to the Justice Department, his appointment ended on Monday.