The Department of Homeland Security has implemented agreements under the Intergovernmental Personnel Act, allowing non-federal employees / "private contractors" to be temporarily assigned to a federal agency to meet needs.

 

In February 2006, for the Super Bowl, some Canadian border enforcement officers were deputized so they could make arrests on either side of the border.

 

Indeed at the Mexican border they have been cross-deputizing Mexican and U.S. border patrol officers in joint operations between the ports of entry.

After Hurricane Katrina they deputized Blackwater mercs to patrol the city.

US Northern Command's "fusion centers" created all over the country coordinate between not just state, local and federal law enforcement, but also involve the military, private sector companies and other non-law enforcement government agencies. Basically, what the system does is deputize every state and local law enforcement officer to be an intelligence collector for the intelligence community, and then some.