The tension between intellectual property owners and user-generated video sports replays came to a head when Twitter deactivated two popular sports accounts: Gawker Media’s Deadspin, with more than 887,000 Twitter followers, and @SBNationGIF, an offshoot of Vox Media’s SB Nation. The takedown came in response to complaints from the National Football League. But critics note the fuzzy line between fair use and IP infringement; some sports leagues, such as the NBA, regard user-generated videos as marketing, not infringement.

The Washington Post notes that, “since the start of the NFL season five weeks ago, the NFL has filed at least 59 complaints, mostly against Twitter and Periscope.”

Third party companies also help leagues police the Web. The NFL hired London-based NetResult, which “monitors the Internet and files grievances on the league’s behalf.” A search for “NFL” on online database Chilling Effects Clearinghouse, which collects infringement and takedown notices, found 6,500 complaints.

While the NFL says it’s just protecting its intellectual property, experts note how difficult it has become to monitor and protect this legal space.

“The practical challenge here is not easy to deal with,” says Ryan Vacca, director of the Intellectual Property Center at the University of Akron School of Law. “With social media, there’s so many actors involved in the process, it’s very tough to police, especially if you’re working in an industry that’s time-sensitive as sports is.”

A recent decision by the U.S. Court of Appeals for the Ninth Circuit also ruled that copyright holders “must consider the existence of fair use before sending a takedown notification,” which analysts say could “expand the interpretation of fair use and force leagues to think twice before filing a complaint.”

Not all leagues take the NFL’s tack; the National Basketball Association interprets the sharing of fan videos a different way. “For the most part, highlights are also marketing,” says NBA commissioner Adam Silver. League executive Mike Bass agrees. “We have always believed that fans sharing highlights via social media is a great way to drive interest and excitement in the NBA,” he says.