The Federal Motor Carrier Safety Administration said it will not delay enforcement of the latest changes to the hours-of-service rules for truck drivers, saying that American Trucking Associations did not demonstrate enough harm to the industry and law enforcement to merit such a delay.

“Mere uncertainty over the possible outcome of the litigation, which you recognize is a matter over which the parties differ, does not create likelihood that the industry or the enforcement community will suffer harm due to wasted training resources or confusion,” FMCSA wrote in a letter to ATA, which the agency provided to Transport Topics.

ATA had asked FMCSA in a Jan. 25 letter to hold off enforcing the rule until three months after ATA’s pending lawsuit is decided.

The federation, which is suing in federal court to have the rule overturned, said the industry and law enforcement would need months to train and prepare for the changes.

In a lawsuit filed in February 2012, ATA asked the Court of Appeals for the District of Columbia Circuit to overturn the changes, saying the agency overstated the role fatigue plays in truck crashes and that the new rule is too restrictive.

Oral arguments before the appeals court are scheduled for March 15.

David Osiecki, senior vice president of policy and regulatory affairs at ATA, said he was “disappointed” by FMCSA’s decision.

“FMCSA’s response means that carriers, shippers and FMCSA-funded state enforcement agencies will have to spend time and money on training and adapting systems to a rule whose final form will not be certain until the court issues its decision,” Osiecki said.

The Commercial Vehicle Safety Alliance also asked for the delay, and the Owner-Operator Independent Drivers Association agreed.

The changes, set to take effect July 1, restrict how drivers can use the optional 34-hour restart to reset their weekly driving limits of 60 hours in seven days, or 70 hours in eight days.

Drivers will be able to use the restart only once every seven days, and it must include two periods from 1 a.m. to 5 a.m.

Under the new regulation, drivers will also have to take a 30-minute break before driving more than eight hours continuously.

ATA has not yet asked the D.C. court to force FMCSA to delay the changes. Osiecki said the group is “currently considering our options” for court action.