[patricklynch]

I don't think it works that way. If you add logic that says:

"here's group A, who we really want to target, and here's group B, the protected class we want to exclude. throw 10% of all impressions at group B so we're not violating federal law."

Then I think you may still be breaking the law. Because you're explicitly favoring one group over another. Whether the ratio is 100%/0% or 90%/10% probably doesn't affect the underlying legal problem.

> Why ruin it

At some point many years ago society latched on to the idea that "equal opportunity employment" was a civil right worth protecting with federal law. One of the major draws of facebook, if you happen to be an employer not wholly committed to this idea, seems to be that you kind of have a way to effectively bypass it. There are people who would equate "ruining facebook" in this scenario with "protecting fundamental civil rights," which is more important than creating a favorable environment for recruiters.

That's more or less the argument I think.