Last time I looked at the Constitution, Eric the Red isn’t given authority over local law enforcement.
Thats why they’re called guidelines and not directives.
However, implicit in issuing those guidelines is the threat that the DoJ will subject any PD failing to follow them to an invasive and expensive “investigation” for doing so.
We no longer go by the Constitution. The majority of voters in 2008 and 2012 said, via their votes, this is what they want. They are about to reap the fruits of their labor.