Max Brunswick, a lawyer for New Haven-based Acme Rent-a-Car, says his client has a technology that saves lives. But if the state Department of Consumer Protection has its way, Acme’s technology will soon be illegal.

Last October, in a story that garnered nationwide attention, Acme installed global positioning system transponders in its fleet of 100 vehicles. When the system finds a customer going more than 79 mph, Acme levies a $150 fine.

Now the state Department of Consumer Protection wants legislators to introduce a bill — possibly as soon as this year — to make such fines illegal across the board.

In July, the department filed a complaint against American Rental Car, Inc., the company that owns Acme, and held a two-part hearing on the matter. James Fleming, the commissioner of the department, will rule in late November on whether Acme will be allowed to continue its policy.

“We do not want Acme tracking people’s speed or giving arbitrary fines,” said Anna Ficeto, a spokeswoman for the agency.

In a settlement offer rejected by Acme in August, the state asked the company to stop fining drivers and to reimburse those who had already been penalized. About four or five clients have so far been reimbursed anyway, Brunswick and Ficeto said.

Customers are not told when they are fined. Acme charges the fine to a customer’s credit or debit card, and the first notification the customer receives may be a bank statement.

Ficeto said the state first learned of the fines when a man checked his debit card and found that Acme had withdrawn $450 from his account. The customer’s subsequent complaint led to the department’s grievance against the rental company.

The fine created a situation where there was no due process and no way for the customer to challenge the fine, Ficeto said.

“I haven’t heard about anyone making a due process claim against a private business,” Brunswick said.

A customer is fined if the car is traveling at 79 mph for at least two minutes, Brunswick said. The computerized system only notifies Acme under these circumstances, he added, and the company only tracks cars that it believes have been stolen.

Brunswick said every contract clearly informs the customer of the system.

“We have always advised people,” he said. “We even put in a box in [the contract] for them to initial.”

But the state has said that customers have not been given adequate notice that they may be fined for speeding. Acme’s contract has changed three times since the complaint was filed to make the language clearer.

State experts also sought to cast doubt on the accuracy of the GPS transponders.

Robert Baron, the manager of survey operations at the state Department of Transportation, said that anything from high-tension electric lines to powerful personal radios could disrupt the accuracy of the system.

But he said he could not comment specifically on Acme’s system.

“It was problematic because Acme was unable to provide technical specifications,” he said.

Regardless of the state’s complaints, Brunswick said he does not have a problem with the overall fairness of the system.

“There are lots of unfair charges associated with car rentals,” he said, citing $4 gallons of gas and cleanup charges as examples.