The final rule published in October requires lap/shoulder belts on small buses and establishes performance standards for seat belts voluntarily installed on large buses. Under the rule, all buses must also have 24-inch-high seat backs and self-latching mechanisms on seat bottom cushions.

In one petition for reconsideration, the American Association for Justice, a national trial lawyer’s group, argued that the rule offers too great of protection for manufacturers against liability.

"NHTSA continues to allow corporate responsibility to take a back seat to children’s safety," said AAJ President Les Weisbrod in a statement.

Public Citizen also recently criticized the rule. In its petition, the consumer advocacy organization objected to the fact that the seat belt requirement does not extend to large buses.

"This attempt by the agency to punt this issue violates its safety obligations under the law and is an obvious effort to assist school bus manufacturers," Public Citizen President Joan Claybrook wrote in a letter to NHTSA.

Others petitioning against the rule include bus builder Blue Bird, seat manufacturer M2K and a child safety technician, though the petitions appeared to be more concerned with several technical aspects of the standard.