Mark Cuban -- Picked for Jury in Fender Bender Lawsuit

Dallas Mavericks owner Mark Cuban won't be spending Monday afternoon blogging or ripping NBA officials ... instead he'll be deciding someone's legal fate on a jury.

Cuban showed up to Dallas County Civil Court today and flaunted his jury summons on Instagram. As luck would have it -- bad luck -- Cubes got picked for a case!

According to court records ... the "Shark Tank" star and 5 other citizens are hearing a case involving a two-car accident from 2012 -- one driver is suing another for negligence. The trial is expected to wrap up today.

As long as neither party cops to being a Spurs fan, Cuban should be able to remain impartial. And you just know one of his fellow jurors is gonna pitch him a business idea.