Clark v. Commonwealth of Pennsylvania was a Supreme Court case decided in 1983. The case involved a challenge to the Pennsylvania Abortion Control Act of 1982, which imposed certain restrictions on abortion. The plaintiff, Robert Clark, was a physician who provided abortions and challenged the Act on the grounds that it violated the Fourteenth Amendment's Equal Protection Clause. The Supreme Court held that the Act was constitutional, finding that the restrictions were rationally related to the state's legitimate interest in protecting the health of pregnant women. The Court also held that the Act did not impose an undue burden on a woman's right to choose an abortion. The Court further held that the Act did not violate the Equal Protection Clause because the restrictions were not based on gender. In conclusion, the Supreme Court held that the Pennsylvania Abortion Control Act of 1982 was constitutional and did not violate the Fourteenth Amendment's Equal Protection Clause. The Court found that the restrictions were rationally related to the state's legitimate interest in protecting the health of pregnant women and did not impose an undue burden on a woman's right to choose an abortion.

In the Supreme Court case of Clark v. Commonwealth of Pennsylvania, Justice Brennan wrote a dissenting opinion in which he argued that the majority's decision was wrongfully based on an interpretation of state law rather than federal constitutional principles. He argued that under the Fourteenth Amendment, states are not allowed to deny citizens their right to vote without due process and equal protection under the law. In this case, Pennsylvania had enacted a statute requiring voters who wished to change their party affiliation after June 1st before an election year be barred from voting in primary elections for two years following such registration changes. This requirement violated both due process and equal protection rights as it arbitrarily denied some individuals access to voting while allowing others with similar circumstances access; thus creating unequal treatment among similarly situated persons. Justice Brennan concluded his dissent by stating that “the Constitution does not permit States so easily or lightly to abridge fundamental rights” and urged reversal of the majority’s decision because it failed “to accord proper respect for those basic liberties secured by our Constitution."