PHILADELPHIA — The young man in the gray T-shirt grabbed a metal barricade outside the Wells Fargo Center on Monday afternoon and tried to haul himself over. Police officers on the other side pushed him back. Again, the man tried to cross the barrier, only to be pushed back a second time.

On his last attempt, he succeeded, as the officers appeared to accept that he would get over the barricade. But then he was promptly handcuffed using plastic ties and led calmly away.

Arrests and detentions during national political conventions have often spawned complaints that the police were too arbitrary in taking people into custody. But during this summer’s conventions, the police seem to be more restrained.