In most cases an Administration is immunized from lawsuits based on damages due to policy decisions. significantly limits what you can sue "them" for. Private lawsuit can be initiated but would need to be private action (happened with Clinton) but these are put on hold until the President is no longer in office.
Impeachment is the most likely angle. an interesting angle might be *should* individuals have a private right to sue for government's failure to follow the Constitution or damages caused by government action. I posted in here Dale's "Regulatory Bill of Rights" which examines private right of action.
http://www.galtsgulchonline.com/posts/15...

I don't think filing suit would work as Obama would be considered exempt from criminal or civil prosecution except by impeachment. Once he has left office (if that ever happens), he becomes a private citizen and (I think) subject to common law civil and criminal jurisdiction. Of course, by that time, the alleged crimes will have been so embedded in the American framework it might be impossible to get an indictment or cause of action under the then present laws. Comment?