Nearly all adults in the District would be held liable if they fail to report suspected child sex abuse under a bill tentatively approved Thursday by the D.C. Council.

The legislation, which comes in the aftermath of the Penn State University sex-abuse scandal, would greatly expand existing city laws requiring mandatory reporting for government workers, teachers and counselors who work closely with children.

After reports surfaced at Penn State that some adults failed to report potential warning signs of abuse by former assistant football coach Jerry Sandusky, council member Phil Mendelson (D) pushed to broaden reporting laws to cover all but a few exempted adults in the District.

“We are interested in sending a clear message,” said Mendelson, now the council’s chairman, noting that 18 states have similar regulations. “This is a bill that simply establishes a policy, that everyone has to report if they know or have reason to believe a child has been sexually abused.”

But the proposal is prompting some unease about government overreach that would set the stage for a surge in thinly vetted complaints, which could lead to false accusations.

“I think we definitely want to achieve more reporting, but there is definitely some concerns around how [authorities] will handle the level of reports that they will get and potentially false allegations,” said council member Kenyan M. McDuffie (D-Ward 5), a former Prince George’s County assistant state’s attorney. “And does having lots of false allegations have the effect of making it more challenging to prove some of these cases?”

Under the bill, which must be voted on a second time before it goes to Mayor Vincent C. Gray for his signature, anyone 18 or older “with knowledge or reasonable cause” to believe an adult is abusing someone younger than 16 must “immediately” report it to police or Child and Family Services. Violators can be fined $300.

Attorneys and ordained ministers are exempt to protect attorney-client and clergy-penitent privileges. Victims of sex abuse would not be required to report past abuse.

For caregivers, teachers and other government officials covered by existing reporting laws, the bill increases penalties to a $1,000 fine and up to 180 days in jail.

In an interview, Mendelson cautioned that he expects penalties to be rarely enforced. But the legislation comes amid a broader debate about the public’s responsibility to be vigilant of abuse vs. the right to privacy.

In the Penn State case, he noted that a school janitor walked in on Sandusky with a boy near a locker-room shower but never reported it out of fear that he could lose his job.

“After Jerry Sandusky, I asked the question . . . would some of the players of the Jerry Sandusky case, I mean witnesses, would they have been required to report? I got different answers,” he said. “That said to me, our law is not clear.”

While some child welfare advocates supported the bill, the American Civil Liberties Union was “fundamentally opposed,” according to council records.

“It creates a slippery slope in that it forces every person to become a government informant,” testified Art Spitzer, legal director for the ACLU of the Nation’s Capital.

City budget officials appeared to be hesitant about the measure. Last month, the Office of the Chief Financial Officer estimated that the legislation would result in a 15 percent increase in suspected abuse reports, including 90 additional calls per month to the city’s abuse hotline. The office said the bill would cost about $2 million over the next two years to hire additional caseworkers and investigators to handle the expected increase in calls.

But in a letter to the council Thursday, Chief Financial Officer Natwar Gandhi altered his office’s stance by stating the city will be able to afford the increased caseload. With Gray (D) also endorsing the bill, it passed the council unanimously, although McDuffie said he will be closely watching its implementation.

The bill was just one of a several regulatory changes embraced by the council Thursday.

The council also tentatively approved a bill that regulates vehicle-for-hire sedans such as those operated by Uber. The sedan drivers will have to be registered and licensed by the city, agree to serve all areas, provide receipts to passengers, take steps to be handicapped accessible and clearly articulate fares before a passenger trip begins.

The council also approved a bill by council member Mary M. Cheh (D-Ward 3)requiring businesses, excluding restaurants, to keep their doors and windows closed when their air conditioner is running to preserve energy. Violators can be fined $100 for a first offense.

“There is data that shows 20 to 25 percent of energy loss is during the summer when doors are opened,” Cheh said. “That is significant.”