A post-sale restraint, also termed a post-sale restriction, as those terms are used in United States patent law and antitrust law, is a limitation that operates after a sale of goods to a purchaser has occurred and purports to restrain, restrict, or limit the scope of the buyer's freedom to utilize, resell, or otherwise dispose of or take action regarding the sold goods. Such restraints have also been termed "equitable servitudes on chattels".

United States v. Univis Lens Co., 316 U.S. 241 (1942), is a decision of the United States Supreme Court explaining the exhaustion doctrine and applying it to find an antitrust violation because Univis's ownership of patents did not exclude its restrictive practices from the antitrust laws. The Univis case stands for the proposition that when an article sold by a patent holder or one whom it has authorized to sell it embodies the essential features of a patented invention, the effect of the sale is to terminate any right of the patent holder under patent law to control the purchaser's further disposition or use of the article itself and of articles into which it is incorporated as a component or precursor.