A Supreme Court justice cited an unusual source in a decision handed down Monday: Spider-Man.

With all eyes on the nation’s highest court over upcoming decisions gay marriage and Obamacare, the reference was a rare moment of levity from Justice Elena Kagan.

The reference came in her decision on Kimble v. Marvel, in which the court declined to overrule decades-old precedent that kept patent-holders from collecting royalties after a patent expires. In her opinion, Kagan noted the principle of stare decisis, which holds that court’s should hesitate to overturn their own precedents.

What we can decide, we can undecide. But stare decisis teaches that we should exercise that authority sparingly. Cf. S. Lee and S. Ditko, Amazing Fantasy No. 15: “Spider- Man,” p. 13 (1962) (“[I]n this world, with great power there must also come—great responsibility”).

The quote comes not from a legal expert, of course, but from Uncle Ben, who is trying to guide a young Peter Parker to use his superpowers wisely in Amazing Fantasy No. 15, the comic which features the first appearance of Spider-Man. Supreme Court justices also have superpowers, but they come from a Senate confirmation vote, not a radioactive spider bite.

In her opinion, Kagan also quoted the 1967 Spider-Man TV show theme song: “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).”

Read the full opinion here.

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Contact us at letters@time.com.