Suppose you own a business and put out an ad for people who want a job. Many apply. You run background checks, including criminal checks, which are perfectly legal. You learn that some of the prospective employees have criminal records. And you decide you’d rather not have a convicted thief working the cash register at your business or you think it’s better that you don’t hire someone with a violent past, fearing he might hit a customer or fellow worker who looks at him the wrong way.