The photographer Mark Peterson spent several weeks this summer documenting such scenes at Federal Plaza. “It’s an image that I imagine the Administration wants out there—these guys, fully armed and masked and with body armor, arresting people,” he said. “The government is obviously looking at what pictures people are making.” Peterson has come to understand the rhythms of the place. Sometimes the agents make small talk while waiting for hearings to let out. One asked Peterson about the type of camera he uses. Others nicknamed one of his colleagues the goat after they learned that she had won a prestigious photography award.