Originally Posted by SATTSO

It also depends on how long the id has been expired. TSA will except identification expired up to 1 year. Even if the ID is over a year expired, bring it, if it's all you have. You will be questioned, but then proceed through security. But if he has any other ID, such as a SS card, credit cards, heck even a library card, bring those too (at this point other IDs not on the acceptable list are used to help confirm your ID, though most likely you will receive additional screening).