From the New York Times blog:

This morning, a Boston-born performance artist, Yazmany Arboleda, tried to set up a provocative art exhibition in a vacant storefront on West 40th Street in Midtown Manhattan with the title, “The Assassination of Hillary Clinton/The Assassination of Barack Obama,” in neatly stenciled letters on the plate glass windows at street level. . . .

“The Secret Service had to do a whole questionnaire with me,” he said. “It was about an hour of questioning. They asked if I owned guns, if I was a violent person, if I had ever been institutionalized.”

Mr. Arboleda answered no. Nonetheless, he said the Secret Service asked him to take down the exhibition title from the window.

“I’m renting that space; the space was allocated for an exhibition and it’s my right to put those words up,” he said. “They said it could excite someone to do something crazy, like break the window. It’s terrible, because they’re violating my rights. If someone breaks a window, they’re committing a crime.”

He added, “The exhibition is supposed to be about character assassination. It’s philosophical and metaphorical.”

I wonder whether anyone has ever pushed a legal challenge to this generally well-understood, and popular, policy that the Secret Service has certain extraordinary legal powers it can execute in connection with a perceived threat to any person it is in the business of guarding.

It does seem constitutionally problematic.  Because it seems here as if the authorities may have overreacted.

I would prefer merely a broad prohibition on “performance artists.”