There are various on-line services which will run a background check on you for a fee.
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Depending on the kind of job you are applying for, a prospective employer in California may generally look at your employment history, your training and educational history, your driving record, your criminal conviction history, your medical ability to perform the essential functions of the job, and your credit history. There are limitations under federal and state law on when, how, and to what extent this information can be obtained and used by the prospective employer. There are also certain notice requirements the prospective employer must comply with.
If you are concerned about what is being said about you by former employers, you might consider hiring a private investigator to do a reference check for you. There are other companies that offer this service as well.
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There are companies that conduct background checks. You can likely utilize their services to answer most of your questions as to what would come up as a result of a background check done by a prospective employer.
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