When talk about a potential $1 billion tax measure for the BART transit district surfaced recently, Contra Costa Times editorial writer Daniel Borenstein looked for details. There was very little in writing. But a survey had been done, staff members said, and they had presented the results to a committee.

A secret committee. One of 20, Borenstein discovered, that were convened in blatant and systemic violation of California’s Brown Act, which requires cities, counties and other local government agencies to conduct their business in public. The number of secret committees has grown in recent years, but the practice goes back decades.

BART attorney Matthew Burrows, amazingly, defended the practice earlier this week. But at Thursday morning’s BART board meeting, after a scathing editorial in the Contra Costa Times the same day, the board owned up to the problem.

“We need to change the way we do business immediately,” BART Director Joel Keller of Brentwood said. No kidding.

The breadth of this practice, undetected for years, is a stunning reminder of how fragile the public’s right to know really is. Secrecy breeds secrecy. Only constant vigilance can keep it in check. And while a culture of secrecy can take hold anywhere, special districts like BART are more vulnerable, since they don’t receive as much public scrutiny as most city councils.

BART is a good transit system, but the district has never been a model of good government. So it’s no surprise that Santa Clara County’s plan to bring a BART line south from Fremont into San Jose has never entailed joining the BART district. The Santa Clara Valley Transit Authority will build and maintain the line while contracting with BART to run it. And if BART does ask voters for a new tax to replace aging train cars, Santa Clara County won’t be affected. Its voters already have agreed to pay taxes toward construction and operations. That said, the health of this critical transit system is important to the entire Bay Area.

The reasons for secrecy range from unfathomable to ominous. Why should the Finance, Budget and Internal Audit Committee operate behind closed doors? Nothing discussed there should be secret. Nothing. Similarly, there is no legitimate justification for closed-door meetings of the Redistricting Ad Hoc Committee — although we can well imagine some directors hoping to manipulate the new committee to protect their political interests.

To comply with the law and rebuild public trust, BART should eliminate all the closed-door committees. Matters that can’t be discussed in public, such as personnel issues, should be handled by the whole board in closed session. If the board wants standing committees to work on specific issues, those committees should post notices of their meetings along with agendas and any staff reports so that the public knows what will be discussed.

The board hasn’t a prayer of persuading residents of the special district to pay more in taxes if people know the plan was cooked up in secret. And who knows what other plans are out there?

It’s time for a revolution in governance. The public has to assert its right to know.