The state Senate gave preliminary approval Wednesday to a bill that would limit when passengers' conversations can be recorded on public buses and trains.
The bill was spurred by the Maryland Transit Administration's practice of recording video and audio on hundreds of its buses.
The legislation would ban that type of "indiscriminate mass surveillance" of transit riders, said Sen. Robert A. Zirkin, a Baltimore County Democrat who chairs the Judicial Proceedings Committee.
A transit agency would be allowed to record audio only in the vicinity of the driver, if the driver turns the system on during an incident or if the system is automatically activated during a problem such as sudden braking or a crash. There also would be penalties if the audio tapes are improperly disseminated.
The exceptions to allow audio recording in those situations were drawn up after hearing from local transit agencies in Prince George's and Montgomery counties, Zirkin said.
The rules would apply to all transit agencies in Maryland, except for the Washington Metropolitan Area Transit Authority, which operates Metro trains and buses in the D.C. region and is governed by a multi-state compact, Zirkin said.
The issue first came to light in 2012, when the first 10 Maryland Transit Administration buses with audio recording equipment were put into service in the Baltimore region. Signs were posted alerting passengers to the open microphones.
"What they are doing is the reason for this bill," Zirkin said.
Zirkin said his committee determined: "What they are doing is wrong."
Audio recording systems are now in place on 65 percent of MTA's local buses, according to Sandy Arnette, an MTA spokeswoman.
Arnette said recordings are only reviewed after an incident, and only that portion of the recording is saved. Otherwise, the recordings are taped over when the storage drive is full. The agency believes audio recording is a "vital public safety tool," Arnette said.
Arnette said the bill "prohibits a proven, effective public safety tool and puts students and all MTA riders at greater risk." She said the MTA was not consulted on the changes that were made to the bill Wednesday.
The MTA told state analysts that 82 percent of its Metro Subway cars are "audio capable" but the proper circuitry to use the system is not yet installed. Though the MTA doesn't have current plans to record audio on Metro Subway cars, it could do so within six months for little cost.
Light Rail train cars are not outfitted for audio recording, but operator-controlled systems are in the works. MARC trains and commuter buses do not have audio systems and the MTA has no plans to add them.
Similar bills to ban audio recording on mass transit failed in 2013, 2014 and 2015.