Congress doesn't like it when you mess with its sports.

This time, House Democrats are accusing the National Football League of improperly trying to influence concussion research by attempting to take $16 million in funding away from Boston University researcher Robert Stern, whom the NFL apparently didn't like, and instead give the money (and the study) to their preferred doctors. When the NFL didn't get its way, it pulled the $16 million grant – despite explicitly acknowledging that it would have no say in the selection process.

The Washington Post's Cindy Boren writes:

According to ESPN, the NIH did not remove Robert Stern and the NFL backed out of an agreement to pay for the study, the costs of which were absorbed by taxpayers. Stern, a BU professor of neurology and director of clinical research at the school’s center for the study of chronic traumatic encephalopathy, has been critical of the NFL and co-authored a recent paper that suggested that repetitive hits to the head were more significant than concussions in contributing to CTE.

Congress members involved in the 91-page report say taxpayers were stuck with the $16 million bill and essentially called the NFL's actions a thinly veiled attempt to influence research in their favor (presumably in the interest of distancing the league and the sport from links to concussions and CTE (chronic traumatic encephalopathy).

“This investigation confirms that the NFL inappropriately attempted to use its unrestricted gift as leverage to steer funding away from one of its critics,” Rep. Frank Pallone (D-N.J.) said in a statement. “Since its research agreement with NIH was clear that it could not weigh in on the grant selection process, the NFL should never have tried to influence that process.”

When does Congress stick its nose into the world of sports? And why?

Congress has oversight of NIH funding, which explains how it got involved in this particular sports foul-up. In the case of daily fantasy sports leagues, the subject of a hearing earlier this month, members of the House asked whether companies such as DraftKings and FanDuel should be regulated like casinos. And because most sports leagues are considered a form of interstate commerce, Congress has oversight of them, too.

That's why Rep. Joe Barton (R-Tex.) introduced a bill in 2009 that would ban the NCAA from referring to any postseason game as a "National Championship" game unless it was part of a playoff system. The bill went nowhere fast in 2009, but now we have the College Football Playoff. Barton is presumably happy with the end of the BCS era.

It's also the reason behind some of the most famous congressional hearings of the 2000s, when Major League Baseball officials and players were called to testify about steroids.

And despite the attention and media coverage the steroid hearings got, not everyone thought they were the best use of Congress's time. Sen. Bernie Sanders at the time lambasted the media for covering baseball hearings but not other topics – topics that might sound familiar in 2016:

In the video above, we look at key sports issues in which Congress has intervened.