The expected litigation frenzy against mortgage lenders that used “robo-signing” tactics — mass signing and approval of foreclosure documents without verification — has launched, with class actions in Florida and Maine and a lawsuit by Ohio’s attorney general filed this month, all against GMAC Mortgage.

Other purported class actions involving robo-signing have been filed in federal courts in Indiana, Kentucky, Maryland and New Jersey in recent weeks. Lawyers expect many more to follow.