In a phone interview Wednesday, Montgomery said he initially fought the charge without a lawyer because he expected the judge to throw out the case.
"I thought it was pretty much straightforward, that it was pretty clear I had the right to do this," he said.
Yet he was convicted, fined and ordered to perform community service. Montgomery appealed, got a lawyer and was acquitted the next month. He later contacted the ACLU.
The lawsuit notes that Police Commissioner Charles Ramsey issued a memo in September 2011 — several months after Montgomery's arrest — instructing officers to allow themselves to be recorded in public.
The directive came just ahead of the Occupy movement's arrival in Philadelphia, when police ended up in frequent contact with protesters expressing civil disobedience and witnesses recording the ensuing arrests.
But the lawsuit notes two people were arrested for taking photos of a traffic stop about six months after the memo was issued. It also lists several examples of audio- or videotapers being cited before the directive went out.
Roper said the ACLU plans to file at least two more federal complaints in the near future.
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