Undue-burden test is a constitutional test to decide the constitutionality of particular law. State regulations affecting undue burdens are regulated by the courts under the test.
In Morgan v. Virginia, 328 U.S. 373 (U.S. 1946), the court held that “a state cannot impose undue burdens on interstate commerce by simply invoking the convenient apologetics of the police power. There is a recognized abstract principle, however, that may be taken as a postulate for testing whether particular state legislation in the absence of action by Congress is beyond state power. This is that the state legislation is invalid if it unduly burdens that commerce in matters where uniformity is necessary—necessary in the constitutional sense of useful in accomplishing a permitted purpose”.