The reason FISA was passed in 1978 was because successive administrations, culminating in the dire Nixon White House, abused the national surveillance infrastructure.
As early as February 2001, certainly before 9/11, the Bush administration started building a surveillance framework that screams of potential abuse.
After 9/11, the gloves were off, and the Bush administration was operating with impunity.
I can only imagine the abuses that have occurred that have purely political motivations. My earlier response pictured Karl Rove with unfettered access to the "total information awareness" infrastructure designed and built by convicted felon John Poindexter. "A rich kid frat boy driving daddy's Ferrari" is how I visualized it.
The most important issue that needed to be addressed by the pending suits (which will be summarily dismissed when this law is signed) is the degree to which this administration used the surveillance infrastructure that it has built for political gain. Based on the revelation of installations such as the secret room at the AT&T switch facility in San Francisco or the "Quantico loop" built into Verizon's wireless switch fabric in the DC area-- how did this administration, whose raison d'etre is politics over policy -- abuse this capability for partisan gain? We have no facts to base this on -- that's why the suits were important. But if history can be our guide -- and nothing about this administration is subtle or nuanced, everything is telegraphed because they know there won't be any consequences -- then it's pretty clear that the administration has built dossiers on its political "enemies" of unparalleled scope and range. Of course that's just my theory. But there will never been an opportunity to test that theory with evidence, as all the evidence will disappear once the President signs a version of this bill containing immunity.