Less confrontational than spattering fur coats with red paint to promote animal rights, or throwing pies at opponents, glitter bombing generally doesn’t yield dry cleaning bills. But glitter bombs have staying power. Weeks after the incident, the victim will probably still be brushing off pesky, iridescent pieces of the stuff, a tangible reminder of an issue that won’t go away. …

When Mr. Gingrich was glittered, he said, “Nice to live in a free country.” Since then, his position has hardened.

“Glitter bombing is clearly an assault and should be treated as such,” he said in an e-mail. “When someone reaches into a bag and throws something on you, how do you know if it is acid or something that stains permanently or something that can blind you? People have every right to their beliefs but no right to assault others.”