Ask HN: Legality of a Jan 18 SOPA blackout on Google?

I heard some people at a coffee shop today discussing the possibility of convincing facebook and google to shut down all of their services for a day because of SOPA, including google apps. While the anarchist in me was momentarily giddy at the whole idea, the realist makes me assume that there must be SLAs and service contracts for their commercial customers and their larger content providers and advertising partners. As awesome as it would be for Google to shut down everything and confuse the heck out of the world I'm sure the losses due to lawsuits and SLA fines would be massive.