In Twenty Percent. Cases, the Supreme Court of the United States was asked to determine whether a state could impose a tax on the sale of goods imported from another state. The case arose when the state of New York imposed a tax of twenty percent on the sale of goods imported from other states. The Supreme Court held that the tax was unconstitutional because it violated the Commerce Clause of the United States Constitution. The Court reasoned that the tax was a burden on interstate commerce and was therefore prohibited by the Commerce Clause. The Court also held that the tax was discriminatory because it only applied to goods imported from other states and not to goods produced within the state. The Court's decision in Twenty Percent. Cases established the principle that states cannot impose taxes on goods imported from other states. This decision has been cited in numerous cases since then and has been used to protect the free flow of goods and services across state lines. The Court's decision in Twenty Percent. Cases has been cited as an important precedent in the development of the Commerce Clause and the protection of interstate commerce.

In Twenty Per Cent. Cases, the Supreme Court was tasked with determining whether a state statute that allowed for an increase in fees charged by attorneys to their clients violated the Fourteenth Amendment of the United States Constitution. The majority opinion held that such a fee increase did not violate any constitutional rights and thus could be enforced. However, Justice Field dissented from this opinion and argued that allowing states to impose additional costs on litigants would place an undue burden on them and limit access to justice for those who cannot afford it. He further argued that since there is no way of knowing how much money will be needed to pay these increased fees until after litigation has begun, individuals may find themselves unable to pursue legal action due to financial constraints imposed by these extra charges. As such, he concluded that this law should not stand as it violates both equal protection under the law as well as due process rights guaranteed by the Fourteenth Amendment of the United States Constitution