Federal prosecutors have dropped criminal charges against four Bernie Sanders supporters who were arrested after breaching a security fence during the Democratic National Convention last month. 

But seven other protesters who did the same thing outside of the Wells Fargo Center, one day later, will be prosecuted and could face up to a year in prison.

Michele Mucellin, spokeswoman for the U.S. Attorney's Office for the Eastern District of Pennsylvania, confirmed that cases on the four fence-jumpers who were arrested the Tuesday of the convention have dissolved. The court filings, however, were not yet publicly available.

"With respect to the other seven. We are hopeful that the government will make the same decision regarding the second group that were arrested by the federal government the second night," said civil rights attorney Paul Hetznecker, who is representing some of the remaining defendants.

After those first four were charged, Philadelphia Police Commissioner Richard Ross told the media that if protesters penetrate the arena's perimeter fence, it is a federal government matter. Which is to say, prosecution beyond a civil citation would be likely. 

The government could argue that Ross' statements constituted a prior notice. But attorney Hetznecker said all the fence-jumpers acted as if they would only receive a civil summary citation, which 103 individuals received over the four-day convention for things like disorderly conduct and disturbing the peace.

Critics of the law under which all 11 fence-breachers were charged argue that it is overly broad and that it effectively criminalizes protest any place where the Secret Service may be protecting.

Restricting where protesters can and cannot demonstrate near some of the nation's most powerful political figures, Hetznecker said, sends a troubling message.

"If you're legitimately protesting an issue in a location in which you have a right to be based on time, place and manner restrictions and you're removed," Hetznecker said. "It's still a violation of the First Amendment."

One of the seven fence-jumpers who are still facing charges is Jeremy Graber, 31, of Woonsocket, Rhode Island, who had three "throwing knives" in his possession when he was arrested.

Hetznecker said Graber is a paramedic who was carrying the knives to cut gauze and bandages. Prosecutors did not add weapons-related charges to Graber's indictment.