[curryst]

I think that depends on the organization we're talking about. There exist organizations where spies getting in probably should be per se negligence. The CIA and NSA are indisputably in this list. We just don't punish them via lawsuits, because there are better mechanisms for public groups.

The question at hand is whether Twitter belongs in that group. In the general case, I tend to believe no. Twitter has no deterministic means to tell whether a candidate is a risk or not, and they cannot be held liable for actions they couldn't know were illegal.

I do believe they can be held responsible for espionage in the event that they knowingly hired a spy, which seems to be the case here.

If the government believes it is important to national security to prevent Twitter from even unknowingly hiring spies, I think the onus is on the government to nationalize whatever parts need protecting. In this case, they could probably just nationalize the background check portion via security clearances. It doesn't sound like we're at that point, though.