Patrick Leahy, who was sworn in today as president pro tempore of the U.S. Senate and who is now third in line the the Presidency, is a huge Batman nerd. The long-serving New England senator was named to the post by U.S. President Joe Biden, but comic fans likely recognize him from his various appearances in Batman-related media. He appeared most recently playing the role of Senator Purrington in Batman v Superman: Dawn of Justice. Before that, he appeared in Batman Forever, Batman & Robin, The Dark Knight, and The Dark Knight Rises, as well as lending his voice to an episode of Batman: The Animated Series.
In Batman v Superman, the U.S. Senate was holding hearings into activities Superman undertook in a foreign nation which had been perceived as an act of war. Unbeknownst to the panel, Luthor had set the Man of Steel up to look like a murderer, and recruited witnesses to pose as victims of the Kryptonian in front of the US Congress. During the hearings, a bomb went off, killing scores of people, presumably including Purrington.
"We've never had Superman as a witness," Leahy joked at the time. "And we've never had quite as much excitement as you're going to see in this hearing [in the movie]."
Of course, that scene plays a little differently just two weeks after armed rioters tried to overturn the results of the Presidential election by storming the U.S. Capitol during a joint session of Congress, killing five people, damaging the building, and stealing government property.
The president pro tempore serves as president of the Senate during the absence of the president -- that being the president of the Senate, who is the Vice President of the United States, not the President of the United States -- and he may administer the oath of office to senators and to officers and employees of the Senate. Leahy held this role once before, from 2012 until 2015 when President Biden was the president of the senate. This time around, it's likely that the role will come with more repsonsibility, since Vice President Kamala Harris will likely have a lot of work on her plate as the senate president. With a 50/50 split of Democrats and Republicans in the Senate, it means any contentious bill that gets a straight party-line vote will need Harris to serve as the tiebreaking vote.
Leahy has received some criticism in the past for taking a lot of contributions from media companies like Disney and WarnerMedia, who are always lobbying Congress for stronger copyright protetion laws. In May 2011, Leahy introduced the Protect Intellectual Property Act -- PIPA -- which sought to strengthen copyright laws and the way they are enforced online. The bill was harshly criticized by free speech activists, and eight months later a vote on PIPA was tabled until issues with the law could be resolved. It never came back up.