An employment background check is routinely required for people getting jobs in health care and education because these positions require intense interaction with the public and people with criminal backgrounds probably should not be put in a role of responsibility with strangers, depending on the severity and type of their crime. An employment background check is simple to do on the Internet, and large employers generally have a subscription to a service that allows them unlimited checks annually. Even small businesses can benefit from running an employment background check to make sure that the people that they hire are reputable and trustworthy.
Not all crimes keep people from being hired. A minor brush with the law is not something to keep someone from having a job. Someone convicted of a minor crime or a crime when they were very young will probably make a great employee, but hiring known sex offenders for jobs that deal with the public when they are in vulnerable positions, like schools and hospitals, is probably not a good idea. Each employer has its own standards for the types of employment background check standards it employs.