I need some help for an essay for criminal law, can you please let me know a decent area i can right about?

If you are looking to explore case law, an area to look at is developments over the past couple years in the supreme court's treatment of 4th amendment issues. Recently, the court ruled in cases related to car stops and school searches. A couple years ago they said that a resident of a home can object to a warrantless search even if a co-resident grants consent.

If you are looking for an "in the news" type of essay, you could research articles about federal judges taking shots at DOJ over department attorneys not properly disclosing exculpatory information to defendants. The Ted Stevens prosecution comes to mind. The same judge in the Stevens case just approved the dismissal of a big drug case on similar grounds. A Miami judge entered a pretty interesting order in a case down there a couple months ago.