The Fair Credit Reporting Act defines the purposes for which a creditor may obtain a credit report. These purposes are the "permissible purposes" that are created by the Act itself. One of the permissible purposes is to evaluate a consumer's request for credit. Thus, pulling a credit report is fairly automatic in consumer credit applications.
You may also obtain the consumer's report with the consumer's permission. This is the path you must follow when a business applies for credit and you want to check the credit history of the business owners and principals.
Check the sections of FCRA that discuss "permissible purpose."