Below is from the IMSA CODE
http://www.imsaracing.net/2006/competitors/IMSACode.pdf
3.3 IMSA DRIVER’S LICENSE
3.3.1 Every person who drives a car in an IMSA sanctioned event shall possess a current
IMSA competition Driver License. The standard Competition Driver license holder
minimum age is 18 years old except for certain developmental series where the
minimum age will be specified in the Series Standing Supplementary Regulations.
3.3.2 IMSA Drivers holding current IMSA competition license must have a current (issued
within 6 months of the date of the application for the license) completed IMSA medical
examination form.
3.3.3 IMSA competition Driver licenses may be issued to Drivers with appropriate
documented national experience or to holders of FIA Grade C or higher licenses from
their home competition club. Holders of foreign FIA licenses must secure and provide
written documentation of permission from their home competition club.
3.3.4 IMSA provisional competition Driver licenses may be issued to Drivers with proof of prior
experience and/or suitable schooling. Provisional Driver license holders may not
compete in FIA-listed events. Provisional Driver license holders are not eligible for FIA
licenses. Provisional Driver license holders may be upgraded, at IMSA’s discretion, upon
request of the license holder, following suitable experience. Normally, the provisional
license holder will be observed for a minimum of three races.
3.3.5 Drivers with provisional Driver licenses must contact the Race Director via IMSA officials
in pit lane each time they intend to drive a car in practice, qualifying or a race.
3.3.6 “Prototype” Category “LM”P and “LM”GTP Driver licenses, or licenses for other
categories of high performance cars, may be issued to Drivers with suitable experience.
One criterion is an FIA Grade B or higher license.
3.3.7 IMSA, in its sole discretion, may review the qualifications of a licensee at any time after
issuance of a license and may require the licensee to submit to such additional physical
examinations, to submit a resumé to include Driver information and record of
competition, or to pass such additional Driver ability tests, and may take such other
action or require the licensee to take such other action as IMSA may deem appropriate,
to determine whether the licensee continues to qualify for a license under these rules.