Lucy Nicholson/Reuters

Extreme problems require extreme solutions. When wrongdoers are going unpunished, intrusive countermeasures are justified, even if they create new victims. Innocent-until-proven-guilty is nice in theory, but untenable in practice. The state should strike fear into innocents if it leads to fewer victims of violent crime.

Ugly problems don't always have pretty solutions.

These are the sorts of value judgments one expects from supporters of Stop and Frisk, "three strikes" laws, the prison at Gitmo, and racial profiling to stop illegal immigration. They're also the value judgments that Ezra Klein invokes in his endorsement of a California law requiring affirmative consent for sex on the state's college campuses. As he puts it, "Ugly problems don't always have pretty solutions."

For now, let's set aside the hotly contested question of whether affirmative-consent laws are illiberal measures that will have extreme, negative consequences for everyone under their authority, or modest yet vital reforms that do not offend civil liberties. The truth of the matter isn't germane to the present discussion.

Here is what Klein believes:

• The number of sexual assault victims is "far too high," so high as to justify "sweeping" and "intrusive" legal measures–specifically, California's new law.
• This law is "sweeping in its redefinition of acceptable consent."
• The law could define as rape "two college seniors who've been in a loving relationship since they met during the first week of their freshman years, and who, with the ease of the committed, slip naturally from cuddling to sex."
• The law intrudes on "the most private and intimate of adult acts."
• The law's "overreach is precisely its value."
• The law "will settle like a cold winter on college campuses, throwing everyday sexual practice into doubt."
• The law will create "a haze of fear and confusion over what counts as consent."
• If successful, the law will cause all or most college men "to feel a cold spike of fear when they begin a sexual encounter."
• If the law succeeds, "colleges will fill with cases in which campus boards convict young men (and, occasionally, young women) of sexual assault for genuinely ambiguous situations."
• The existence of cases "that feel genuinely unclear and maybe even unfair" are especially necessary for the law to succeed.
• "The Yes Means Yes laws creates an equilibrium where too much counts as sexual assault. Bad as it is, that's a necessary change."

Many proponents of affirmative-consent laws would dispute the way Klein characterizes them, and favor them with the expectation that they won't result in injustice.

That is an unobjectionable stance, whether right or wrong.

To understand California's law as Klein does and to favor it anyway is appalling, if admirably forthright. It is akin to asserting that, to fight sexual assault, we must operate on the dark side. It is a declaration that liberal values aren't adequate after all, using logic Klein rejects when it is applied to other policy areas.

It is also inconsistent with Klein's self-conception as a post-ideological wonk who just follows the evidence where it leads. On what basis does he conclude that California's new law, the costs of which he discusses at great length, will lead to a salutary change in sexual culture, let alone a decrease in campus sexual assaults? The argument he presents for that conclusion isn't just thin, it is virtually absent. There is no citation of similar policies that have succeeded elsewhere, just an implicit assumption that the cultural effect of this "sweeping," unprecedented legislation can be predicted as it filters through the minds of 18-to-22 year olds at institutions as diverse as the University of California at Berkeley and Pepperdine. On the strength of a gut feeling that this could work, Klein is prepared to endorse not a careful pilot program, but a rapid, statewide transformation. The problem is bad. Something drastic must be done. This is something drastic.