Cairo has had a problem with young men catcalling, groping or outright assaulting women on the street since before the revolution that ousted President Hosni Mubarak in early 2011, but it's gotten worse since then. Weak public order, only intermittently present police and a sense of lawlessness appear to have exacerbated street harassment of women, which activists have been at tremendous pains to stop or deter for  two-plus years.

Now some in Cairo appear to be trying a new approach. This video shows activists grabbing two young men who have allegedly just harassed a pair of women. They pin the men against a wall and use a stencil to spray-paint, in Arabic, "I am a harasser" on their T-shirts. The idea, presumably, is to simultaneously shame the men, warn their potential victims and deter future harassment.

The effort is a touch medieval, with hints of the stockade. It's clearly born of despair over conventional methods of enforcing public order, which are in fact working less and less. But it's also vigilante justice, which could arguably undermine what remains of public order rather than promote it. And, like all vigilante justice, it carries the risk of escalation or violence. What's to stop the young men from fighting back? Where's the line between spray-painting street harassers and beating them? Between branding people for street harassment and branding them for, say, supporting the wrong political party?

Efforts like this are understandable reactions to the decline of public order in Egypt. But rule of law isn't just about public order, it's also about having an agreed-upon set of rules and methods of accountability that apply equally to everyone. Vigilante justice isn't a cure for the larger breakdown in post-Mubarak Egypt; like the street harassment it's attempting to stop, it is a symptom.

(Hat tip to Cairo-based journalists Sarah Carr and David Kenner.)