The Edgar v. Mite Corp case in 1981 revolved around the Illinois Business Take-Over Act, which was challenged by Mite Corporation as it interfered with their attempt to take over another company. The Supreme Court ruled that the act violated both the Commerce Clause and Supremacy Clause of the U.S Constitution. The court found that Illinois' law placed an undue burden on interstate commerce because it allowed state officials to review and reject any takeover bid involving a corporation with assets in Illinois, regardless of where those corporations were based or incorporated. Furthermore, they determined that this law conflicted with federal securities laws which aimed at full disclosure rather than substantive fairness evaluation for corporate takeovers. Therefore, they concluded that such state regulation was preempted by federal law.

In the dissenting opinion for Edgar v. Mite Corp., Justice White, joined by Justices Brennan and Marshall, argued that Illinois law did not violate the Commerce Clause of the Constitution. They contended that states should have a right to regulate takeovers of companies within their jurisdiction as long as they do not discriminate against out-of-state interests or burden interstate commerce excessively in relation to local benefits. The dissenters believed that this case was different from previous ones because it involved securities regulation - an area where states traditionally had authority until Congress decided otherwise. They also disagreed with majority's view on First Amendment grounds, arguing there was no evidence showing Illinois' law would suppress truthful information about tender offers or prevent shareholders from making informed decisions.