PENNSYLVANIA and New

Jersey rely mostly on doctors, relatives, friends and neighbors to report potentially unsafe elderly drivers, but dozens of states take a more proactive approach.

Illinois' law targeting senior drivers is the nation's most restrictive, requiring all drivers 75 and older to pass a road test. Last year, 157,706 tests were administered in that age group and 21,104 were failures, about 13 percent. Some took the test more than once.

"Eyesight or reaction time might deteriorate with advanced age. This just helps ensure that Illinois' roads are safe," said Henry Haupt, spokesman for the Illinois Secretary of State's Office.

Washington, D.C., requires seniors to pass a vision test and get a physician to assess their competency to drive, and several states accelerate their license-renewal cycle to two years or prohibit mail renewal for elderly drivers, according to the Insurance Institute for Highway Safety.

Age-based driving laws are often attacked as discriminatory by groups representing seniors. New Hampshire state Rep. Bob Williams, 84, succeeded this year in repealing mandatory road tests for older drivers.

But Haupt said Illinois' law is not discriminatory because it restricts seniors' driving privileges only if they can't pass the test.

"We've always said that anyone that can pass the exam deserves to be licensed, regardless of age," he said.