HARRISBURG, Pa. In February, motorcoach drivers across the U.S. began receiving letters from their state licensing agencies informing them they had to bring in a copy of their medical examination certificate.

The letters also told drivers that if they ignored the mandate they could be at risk of losing their commercial drivers license.

The new requirement resulted from a rule adopted by the Federal Motor Carrier Safety Administration four years ago that went into effect at the end of January. (See Nov. 15 and Dec. 1 issues of Bus & Motorcoach News.)

The feds are giving states and drivers two years in which to fully comply with the rule.

Most states reportedly plan to require drivers to submit their certificates based on when their current CDL expires, which will allow the states to stretch out the filing over the full two years. Otherwise, state agencies could be overwhelmed by drivers bringing in their certificates.

The process of a driver taking his or her medical certificate to a state licensing agency and getting it recorded is called self-certification.

The requirement applies to all CDL holders who drive interstate. Drivers who never drive outside the state in which they are licensed dont have to self certify, but they must provide evidence to the licensing agency that they only drive intrastate.

Some states, like Pennsylvania, have had to adopt special legislation to amend their state vehicle code to permit the self-certification process.

Last month, Pennsylvania Gov. Tom Corbett signed legislation that cleared the way for that state to begin implementing the self-certification program. Pennsylvania has more than 400,000 CDL holders who must be certified no later than Jan. 30, 2014.

Pennsylvania is among the states requiring drivers to submit their certificates based on when their CDL expires.

The Pennsylvania Bus Association and other state transportation-related associations worked with the general assembly and political leaders to get the self-certification legislation passed on a timely basis so PennDOT could meet its implementation goals.

"The Pennsylvania Bus Association is proud to have been a part of the legislative process that made this happen and to have been invited to Gov. Corbetts signing of HB 1458," said Elaine Farrell, executive director of the Pennsylvania Bus Association.