He calls himself the Weed Man, and he has become a familiar presence in Times Square, standing near Planet Hollywood and holding aloft a placard that stands out even in this part of the city.

“Help!” the sign, in green letters, reads. “I Need Money for Weed!”

The man, Joshua Long, has become a favorite of some tourists who pose for pictures with him and stuff dollar bills into his hand. But some police officers in Midtown have taken a dim view of his entrepreneurial spirit and, perhaps, the words that further it; they have arrested him several times while he was displaying his placard.

Once, he said, officers told him he was not welcome on Broadway because they objected to his message. When he asked those officers to identify themselves, he said, they replied by arresting him.

In July, Mr. Long sued the city and several police officers in Federal District Court in Manhattan, saying that he had been subject to illegal harassment and arrests “while lawfully begging and promoting marijuana tolerance.”