The Maryland Senate on Tuesday delayed action on a bill that would clamp down on when public buses and trains can record the private conversations of their passengers.

Sen. Robert A. Zirkin (D-Baltimore County), chair of the Senate Judicial Proceedings, which unanimously voted for the measure to move to the Senate floor, said he wanted the committee to address an amendment offered by some of those who are concerned about costs associated with the bill.

The bill is likely to be considered by the Senate on Wednesday, he said.

“What [the Maryland Transit Administration] is doing is a mass surveillance,” Zirkin said.

“I find it outrageous,” he said. “I don’t want to overstate it, but this is the issue of our generation. As technology advances, it becomes easier and easier to encroach on people’s civil liberties.”

While Zirkin and other proponents argue that the technology, which has been in use since 2012, is an infringement on civil liberties, the bill’s opponents say the recordings are a necessary tool for homeland security.

The bill, which would affect MTA buses in the Baltimore area, Ride On buses in Montgomery County and TheBus in Prince George’s County, creates guidelines for audio recordings and places limits on when they can be made.

[On buses, cameras are watching and listening]

MTA began using recording devices inside some of its buses in 2012, without seeking legislative approval. Nearly 500 of its fleet of 750 buses now have audio recording capabilities. Officials say the devices can capture important information in cases of driver error or an attack or altercation on a bus.

Under the bill, recording devices would have to be installed near a bus or train operators’ seat. The devices would be controlled by the driver and could be activated only in the event of a public-safety incident.

The legislation to limit the recordings came to the Senate floor last week, but a vote was delayed until Tuesday after several lawmakers raised questions about how much it would cost to retrofit or replace existing recording equipment to meet the bill’s requirements.

Some lawmakers raised the issue of security. Several asked for the delay to allow time to draft amendments.

“I can make an argument to tape everybody, everywhere, everywhere they walk, everywhere they talk, and you can make the excuse for homeland security,” Zirkin said. “But that is not a valid reason to encroach this fundamentally on people’s privacy rights.”

This is the fourth time in four years that the bill to limit the recordings has been introduced. Previous pieces of legislation have never made it out of committee, but Zirkin’s committee unanimously approved it this year.

Senate President Thomas V. Mike Miller Jr. (D-Calvert) indicated last week that he doesn’t like the bill and would probably vote against it because he feels the limitations could compromise security, and he does not want to incur the cost of replacing existing equipment.

The Judicial Proceedings Committee will hear testimony Tuesday afternoon on a bill that would change the way police officers in Maryland are trained and the process they go through when they are accused of misconduct.

The legislation, which was heard in the House last week, was created after the spring’s riots in Baltimore and repeated calls from criminal justice advocates for police reform.

Also on Tuesday, the House Appropriations Committee is scheduled to hold a hearing on a proposal to ban firearms at public colleges and universities in the state, including community colleges. Under existing law, schools can set their own gun policies, as long as they comply with Maryland statutes. Some schools prohibit firearms outright, while others allow them with permission from campus police.

[Md. Democrats pushing to strengthen state’s already strict gun laws]

The gun legislation, sponsored by Sen. Richard S. Madaleno Jr. (D-Montgomery) and Del. Benjamin S. Barnes (D-Prince George’s), is partly a response to a wave of mass shootings across the nation in recent years. Schools that include Virginia Tech and Oregon’s Umpqua Community College have experienced such deadly shootings, and Washington College on the Eastern Shore was shut down for a week in the fall while authorities tried to track down a student who had allegedly displayed a gun on campus.

House Speaker Michael E. Busch (D-Anne Arundel) and Senate President Miller joined other Democratic lawmakers in announcing support for the gun ban last month.

Josh Hicks contributed to this report.