In Andrus v. Allard (1979) 444 U.S. 51, regulations of the Secretary of the Interior which prohibited commercial transactions in parts of birds legally killed before they came under the protection of relevant statutes were challenged. The high court upheld the validity of those regulations. The court stated (at p. 58) that: "It was reasonable for Congress to conclude that the possibility of commercial gain presents a special threat to the preservation of the eagles because that prospect creates a powerful incentive both to evade statutory provisions against taking birds and to take a large volume of birds." The respondents in Andrus contended that the goal of preventing evasion of the statute could have been achieved by means less onerous than a general sales ban. At this point, the court noted: "Moreover, even if there were alternative ways to insure against statutory evasion, Congress was free to choose the method it found most efficacious and convenient. 'The legislature . . . is authorized to pass measures for the protection of the people . . . in the exercise of the police power, and is itself the judge of the necessity or expediency of the means adopted.' " ( Andrus v. Allard, supra, 444 U.S. 51, 58-59.) The court also recognized that a flat prohibition on the sale of wildlife is a valid, traditional conservation technique, and "a traditional legislative tool for enforcing conservation policy." ( Andrus v. Allard, supra, 444 U.S. 51.)