It's been a while since law school, but:
Laches is a doctrine of equity (as opposed to statute law) that dictates whether one loses one's rights to an action due to inattention, during which time the supposed malefactor relied on the lack of objection to conclude that the activity in question was neither actionable nor improper. This doctrine arose to prevent those with potentially valid claims from waiting until the supposed malefactor had gotten way out on a limb before chopping it off, because this sort of 'ambush' litigation was considered to give the potential claimant too much leverage. Laches generally cannot apply where there is a specific statute of limitations that apllies to the type of action in question, but where the period of limitation is very long (say, ten years), laches sometimes still has an application within a lesser period of time, depending on the facts (and what the judge had for breakfast).
Mark Schynert