[2] The Smith Act was written after the Pennsylvania Sedition Act, but both were created during the Cold War, during the age of Joseph McCarthy and his House Unamerican Activities Committee; this was the time of the "Second Red Scare", when McCarthy investigated many people accused of communist activities.

[3] The Case was argued in front of the Warren Court whose members were: Earl Warren; Hugo Black; Stanley Reed; Felix Frankfurter; William O. Douglas; Harold Burton; Tom C. Clark; Sherman Minton; and John Marshall Harlan II.

This is known as preemption: "a situation where a legitimate exercise of national authority supersedes any conflicting action by a state government.

"[5] The Court had to decide whether or not the Pennsylvania law could work concurrently with the Smith Act of the Federal Government.

The Smith Act of 1940 criminalized sedition against the United States and since the Pennsylvania Sedition Act did essentially the same thing, Chief Justice Earl Warren wrote in the opinion of the court that federal law is preeminent, giving three conditions for Federal preemption: The presence of these three conditions meant that congress had chosen to "occupy the field" and thus the states could not regulate within it.

The first thing that he stipulates is that, "... the decision in this case does not affect the right of States to enforce their sedition laws at times when the Federal Government has not occupied the field and is not protecting the entire country from seditious conduct.

The first caveat, whether "the scheme of federal regulation [is] so pervasive as to make reasonable the inference that Congress left no room for the States to supplement it", is answered by Warren by noting that Congress, besides the Smith act, had issued The Internal Security Act of 1950.

Warren emphasizes that Congress made these acts to provide for the common defense, to preserve the sovereignty of the United States as an independent nation, and to guarantee to each State a republican form of government, and that these concerns are in no way a local concern.

He points out that Franklin D. Roosevelt had revealed this discrepancy in the Pennsylvania law earlier : Unlike the Smith Act, which can be administered only by federal officers acting in their official capacities, indictment for sedition under the Pennsylvania statute can be initiated upon an information made by a private individual.

The opportunity thus present for the indulgence of personal spite and hatred or for furthering some selfish advantage or ambition need only be mentioned to be appreciated.

"The 'occupation of the field' argument has been developed by this Court for the Commerce Clause and legislation thereunder to prevent partitioning of this country by locally erected trade barriers", wrote Reed, "In those cases, this Court has ruled that state legislation is superseded when it conflicts with the comprehensive regulatory scheme and purpose of a federal plan.

"[10] Reed argues that Congress has not occupied the field with the Smith Act, and that it doesn’t need to, and by doing so is undermining state power.

… This Court has interpreted the section to mean that States may provide concurrent legislation in the absence of explicit congressional intent to the contrary.