Excerpts from the New York Times:
The federal government has significantly expanded undercover operations in recent years, with officers from at least 40 agencies posing as business people, welfare recipients, political protesters and even doctors or ministers to ferret out wrongdoing, records and interviews show.
At the Supreme Court, small teams of undercover officers dress as students at large demonstrations outside the courthouse and join the protests to look for suspicious activity, according to officials familiar with the practice.
The agents, often youthful looking, will typically “dress down” and wear backpacks to blend inconspicuously into the crowd, the official said.