Got it.
Glenn Reynolds (University of Tennessee law prof) at
Instapundit agrees that it's a state issue and that federal legislation would be required to protect people photographing police. In Popular Mechanics he writes on
Taking Photos In Public Places Is Not A Crime:
Police and prosecutors in Maryland have been taking a particularly hard line. In one case, motorcycle rider Anthony Graber left his helmet cam on while he was pulled over by a state trooper. A grand jury indicted him on several violations of the state's wiretapping laws. If convicted on all charges, Graber could face up to 16 years in prison. In alleging that the GoPro video camera on Graber's helmet constituted a "surreptitious" wiretapping device, prosecutors are making the claim that a person recording his own arrest is violating the police officer's right to privacy.
This is the sort of thing you might be tempted simply to toss in the crazy file. But, in fact, this is one of the comparatively few issues that could merit a new federal civil rights law. Under the 14th Amendment to the Constitution, Congress is empowered to pass laws protecting civil rights against infringement by state and local officials, and that seems to be what's happening here. A clear federal law would limit cases, like Maryland's, in which local officials use their power to harass those who might keep an eye on them. Passing such a law would make us all safer.