Anticipating that the US federal government would invoke the so-called “state secrets” privilege to block any lawsuit calling for the disclosure of details about allegations that phone companies shared customer records with the government’s biggest spy agency, a major civil rights group has embarked on an alternate course.

The American Civil Liberties Union (ACLU) has filed complaints in more than 20 individual states demanding that their utility commissions and attorneys-general convene public hearings and call phone company executives to testify.

The ACLU action in Massachusetts is typical of the approach being taken by the civil rights group. Carol Rose, executive director of the ACLU in Massachusetts, said four mayors had complained to the state’s utility regulatory board, where state law requires the board to conduct public hearings when a mayor complains.

Michael D. Bissonnette, mayor of Chicopee, Massachusetts, said he joined the requests because privacy was fast becoming the key civil rights issue.

“This is likely the greatest invasion of consumer privacy in our nation’s history,” he said.

The ACLU filed similar complaints in 20 other states.

Typically, state utilities commissions are mandated to regulate the activities of telephone and other electronic carriers operating in their respective states.

A full-frontal legal assault on the National Security Agency would likely hit the brick wall of the “state secrets” doctrine — through which the government is able to keep sensitive cases from ever coming to trial because public disclosures would compromise national security. Once rarely used, the state secrets privilege has become one of the staple defenses used by the Bush administration to maintain secrecy.

The ACLU has also launched a nationwide campaign to encourage citizens to make their utility commissions aware of their privacy concerns.

The group is running full-page ads in eight large-city newspapers asking the public to join the complaints. The ads claim that telecommunications companies including “AT&T, Verizon and Other Phone Companies May Have Illegally Sent Your Phone Records to the National Security Agency.”

The civil rights group has also asked the US Federal Communications Commission (FCC) to reconsider its recent decision not to investigate the alleged provision of tens of millions of telephone records to the National Security Agency (NSA). The NSA is the largest of the government’s spy agencies and both the creator and executor of the massive program.

The phone-records issue was exposed after a newspaper, USA Today, reported the program on May 11. It charged that three major national phone companies — AT&T, Verizon, and BellSouth — had turned over the call records of millions of Americans to the US government in the wake of the Sept. 11 attacks.

President George W. Bush and other administration officials have neither confirmed nor denied the USA Today report. But Bush has said the administration’s anti-terrorism surveillance programs are legal and constitutional.

Meanwhile, attorneys who specialize in class action lawsuits are preparing to file a blizzard of suits against the phone companies purportedly involved with the NSA program. The ACLU of Illinois has already filed suit against one of the suspect phone companies, AT&T, charging that its actions in the NSA program violated customer privacy.

But it remains unclear which phone firms handed over what records to whom. Some companies have denied involvement. All the companies named by USA Today have disputed the newspaper’s account. AT&T has neither confirmed nor denied it, but has said that no information was released illegally.

Verizon has flatly denied involvement in the NSA program. BellSouth issued a statement earlier this month that said, “Based on our review to date, we have confirmed no such contract exists and we have not provided bulk customer calling records to the NSA.” The ACLU believes the phone program is the latest example of “a longer-term abuse of power by the executive branch,” said executive director Anthony D. Romero.

Civil liberties lawyers have questioned the legal basis that Attorney General Alberto R. Gonzales has used to justify the constitutionality of collecting domestic telephone records as part of the Bush administration’s anti-terrorism program.

The phone records at issue do not contain the names or contents of calls, but do list which numbers called which other numbers, both internationally and domestically, and how those calls were routed.

In April, the ACLU and other civil rights, journalism and business advocacy groups who frequently communicate by phone and e-mail with people in the Middle East, filed suit against another NSA program, the so-called Domestic Surveillance Program, through which the NSA eavesdrops on international telephone calls and e-mails, one end of which is in the US.

Oral arguments are currently scheduled for June 12, and it is widely expected that the government will invoke its “state secrets privilege” to keep the case out of court.