What is the current state of the law on "sideswitching" in civil litigation?

Compare General Motors Corporation v. City of New York, 501 F.2d 639, 650 (2d Cir.1974) ("Indeed, the question of `sideswitching,' and of the conflict of interest which is almost certain to arise when counsel changes sides is addressed by Canon 4 and not Canon 9. * * * The ethical problem raised here, we repeat, does not stem from the breach of confidentiality bred by a conflict of interest but from the possibility that a lawyer might wield Government power with a view toward subsequent private gain.").