NEW YORK, NY - Spiderman attends 'The Amazing Spider-Man 2' Be Amazing Day Volunteer Day on April 25, 2014 in the Queens borough of New York City. (Photo by Mike Pont/Getty Images)National Journal

A Spider-Man comic— specifically, "Amazing Fantasy No. 15: Spider-Man"—now has a special place not only in the hearts of America's nerds, but also in Supreme Court precedent.

The Court very rarely overturns its own precedents—even though it can and even when doing so would have helped out a guy who just wanted to make a few bucks off the Spider-Man toy he invented.

And to explain that principle, Justice Elena Kagan on Monday turned to the superhero himself, officially citing the comic book in which Spider-Man made his debut. "What we can decide, we can undecide. But "¦ we should exercise that authority sparingly," Kagan wrote.

"[I]n this world, with great power there must also come—great responsibility," Kagan added, attributing the line to Stan Lee and Steve Ditko in the 1962 comic.

Specifically, the Court said Marvel—the creators of Spider-Man—did not have to keep paying royalties to the inventor of a toy that, in the Court's description, "allows children (and young-at-heart adults) to role-play as 'a spider person' by shooting webs—really, pressurized foam string—'from the palm of [the] hand.'"

The inventor, Stephen Kimble, patented the toy. Then he tried to sell or license the patent to Marvel—the creators of Spider-Man. (Kagan: "Kimble met with the president of Marvel's corporate predecessor to discuss his idea for web-slinging fun.")

Marvel passed, but then started selling its own, similar product, called the Web Blaster. Kimble sued, Marvel settled, and Kimble received a royalty for future Web Blaster sales.

"The parties set no end date for royalties, apparently contemplating that they would continue for as long as kids want to imitate Spider-Man (by doing whatever a spider can)," Kagan wrote Monday.

Kimble's patent expired in 2010, and Marvel wanted to stop paying him royalties. The Supreme Court has previously said that companies in Marvel's position can quit paying royalties when a patent expires. Kimble asked the Court to overrule that decision, arguing that it's stifling innovation.

The Court, led by Kagan, declined. It's a big deal to overturn a precedent, Kagan wrote, and this case didn't rise to that standard. Even if patent law does discourage innovation, she said, that's Congress's problem. In the meantime, the law clearly limits patent protection to 20 years.

Or, in Kagan's, words, "patents endow their holders with certain superpowers, but only for a limited time."

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