A ban on panhandling in BART trains wouldn’t violate the First Amendment, the agency’s staff said in a new legal analysis that rattled an already tense debate among board directors.

It’s the latest development in a fight that keeps flaring up, as officials weigh the rights of people to entertain and ask for money against the rights of riders to be left alone. Supporters of panhandling restrictions say the practice intimidates and annoys commuters. Opponents fear such a law would penalize poor people and street artists, including some who create a vibrant atmosphere at BART.

Transit agencies in New York, Los Angeles, Atlanta, Chicago, Seattle and Washington, D.C., already prohibit panhandling in their paid areas. They permit busking and other forms of artistic expression in designated spaces within the transit system, though in Atlanta, any such activity must be approved by the Metropolitan Atlanta Rapid Transit Authority.

The findings emboldened BART board Director Debora Allen, who is pressing for a ban that could affect everyone from guitar strummers, to vendors hawking tissues, to dancers, to people wandering through the trains with cardboard signs.

The transit agency already has a policy against aggressive panhandling, which might include touching, threats or the invasion of personal space. It was crafted in 2017 — not to prevent people from seeking donations, but to provide clarity for police officers. Before the rule was enacted, officers routinely detained innocuous and nonviolent panhandlers, according to BART’s independent police auditor, Russell Bloom. These incidents sometimes devolved, leading to an arrest or use of force that could have been avoided, Bloom said.

While the transit agency has tried to clamp down on aggressive behavior, it’s largely permitted busking and other forms of solicitation that are so ubiquitous they’ve become part of the day-to-day commute for many Bay Area residents.

“Five of the ten largest transit systems in America all prohibit panhandling and/or solicitation inside of their paid areas,” Allen said in a statement released Monday. “New York, LA, DC, Atlanta, and Chicago all have ordinances. There is no reason why BART shouldn’t make it six, as we are the fifth largest transit agency in America. People come to San Francisco from all over the world and they are shocked by what they see on our transit system.”

Allen provoked an outcry when she first floated the idea in August, causing arguments to unspool on social media and carry over to BART’s Board of Directors. The American Civil Liberties Union vigorously challenged the proposal, calling it restraint on free speech and citing a 2017 case in Sacramento, in which a federal judge quashed a city panhandling ban because it infringed on free speech.

“(Government) entities that have tried to pass these ordinances have not been successful,” said ACLU staff attorney Abre’ Conner. “Instead of wasting resources trying to criminalize people who ask for help, BART should be trying to figure out how to make their trains safe and accessible for everyone.”

But BART’s situation is different from Sacramento, agency staff said in their analysis, which they will present to the board on Thursday without a recommendation either way. Whereas the Sacramento ordinance repressed speech in a traditional public forum, BART’s ordinance would apply to a “non-public forum,” staff said, because people pay to get in. The presentation noted that any restrictions need to be “reasonable and viewpoint neutral,” and defined clearly enough to prevent arbitrary or discriminatory enforcement.

That reasoning failed to convince board directors on the other side of the issue, who say a panhandling ban would curtail civil liberties without making BART any safer or more pleasant.

“Panhandling is also me standing at the station with my kid, 50 cents shy of getting out and asking the person next to me for help,” Director Lateefah Simon said. “We have a policy on the books ... to keep people safe. Banning speech is not going to do that.”

Director Janice Li, who also objects to the ordinance, said she hasn’t heard any member of BART’s staff endorse the proposal.

“I have done long walk-throughs with BART police and the San Francisco Homeless Outreach Team ... and I’ve never heard any of them say this is something that’s going to assist their operations, or make BART better or safer,” she said.

Passengers appear divided on the proposal, yet it’s gathering support from station agents and custodians who constantly deal with panhandlers. In comments submitted for the staff report, one station agent described people positioning themselves at ticket machines to beg for money. Others said panhandlers block stairwells and escalators.

“All shift long, tourists give in to them, uncomfortable,” a station agent said. “The customers let go of the money. Then, they come to my booth asking why this is happening. What can we do?”

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan