"There is one transcendent advantage belonging to the province of state governments, which alone suffices to place the matter in a clear and satisfactory light ... I mean the ordinary administration of criminal and civil justice."
The current political missteps of the Department of Justice have shown this to be the case, and a succession of disastrous appointments by the Obama administration to go after local law enforcement for policy transgressions such as Sheriff Arpaio in Maricopa County have certainly led credence to why the Federal Government can't be trusted with a national law enforcement agency.
And we can see now, where the feds get involved in legitimate law enforcement matters its a complete disaster. Thirteen years ago the FTC opened the National Do Not Call Registry, probably at a cost of many millions of dollars, to prevent people from receiving telemarketing calls. After 13 years and many revisions the program is completely ineffective and a waste of money. I myself receive between five and ten telemarketing calls a day, and don't answer my phone anymore, unless I can identify the number calling. The feds thought that enacting a law without enforcement would be sufficient. In 2009 the Obama administration declared victory in their 2009 Economic Report. The telemarketers are declaring victory every time my phone rings.
An even bigger failure is the feds enforcement of cyber security. My wife called me in a panic this morning because someone is sending out emails with virus attachments from an email address from her business. Someone spoofed the address, the attacker appears to be coming from China. Many of our government agencies have been hacked from foreign lands without repercussion, and many of our businesses. The federal government spends eighty billion a year on cybersecurity and many claim it isn't enough, that more needs to be spent. I beg to differ. More needs to be done not spent. But my point still is, the government does many things poorly, and as Hamilton points out, law enforcement is one of them.
Separation of powers was also meant to dilute the power of the federal government, with respect to the states. The word federalism itself is the system of government where the power is divided between state and federal governments. The twentieth century, and now the 21st has seen a steady erosion of federalism with the federal government taking more power with less success, more power inflicting the EPA on businesses, and the wielding of the federal budget to punish local governments that get out of line, whether it be law enforcement or education. This is the exact opposite of what the founders intended. The intended purpose of the federal government was to regulate state-to-state commerce and promote the federal defense. Erosion of local power, rampant crime, and an all powerful single federal government was the exact opposite of their intentions and the states would have never ratified the constitution if they knew the behemoth the federal government would grow into, the waste of tax payer dollars, and the wielding of power using money over the states.