When a premises is rent-controlled, the rental rate cannot be arbitrarily changed outside of specific changes endorsed be the regulating authority. In the free market a landlord loses income the longer an apartment remains vacant. Therefore, in the free market, landlords generally have less incentive to discriminate against potential renters. However, when the rent is controlled, would-be renters are more incentivized to pursue such options so as to minimize the risk associated with potential increases in their cost of living. This creates a surplus of applicants for the landlords to choose from that allows them to arbitrarily discriminate against various groups if they are so