Instapundit Glenn Reynolds also writes a column for USA Today - bloggers can become journalists. Today he argues that federalizing the nation's police forces is a bad idea. He mentions the hookers scandal with the Secret Service in Colombia and the FBI crime lab screwing up forensic analysis of hair as examples of Federal crime fighters not covering themselves with glory.
I'd add the FeeBees brought us shootouts at Ruby Ridge and Waco, while ATF brought us the gun-walking Fast and Furious mess on the border. And the CIA seemingly screws up with some frequency too, although to be fair we never hear of their successes, only their failures make the news.
More examples? An NCIS agent was among those busted in the Navy corruption-in-Asia-resupply scandal. Famously, back in the day J. Edgar Hoover is reported to have been a quasi-blackmailer of the mighty to maintain his power.
My point, like Reynolds', is that federalizing the force is no guarantee of clean enforcement. Having a variety of units reporting at several levels causes cross-checking, healthy competition and even a bit of antagonism, meaning a greater likelihood of malefactors getting caught and ratted out.