The Commercial Motor Vehicle Safety Act of 1986 standardized the requirements for commercial driver's licenses across this country. This was brought on by the number of accidents caused by untrained, unsafe, and irresponsible truck drivers who were not prepared to drive these oversized vehicles safely. Prior to 1986, anyone who had a driver's license could drive a commercial vehicle, no matter what the size or how unique the equipment. After that date, federal law required that all truckers obtain a truck driving license after passing both a written test and a driving test. They have to be 21 years old, and in some states, they also have to obtain a special permit for some categories of commercial vehicles, such as tank trucks or those carrying hazardous materials. The law also created a national truck driver's database to monitor the safety of commercial vehicle drivers throughout the country.