A more thorough explanation:

The McCarran Act is a federal law that was passed in 1950 during the Cold War. It required members of the Communist party to register with the Attorney General and for Communist organizations to provide the government with a list of members. The Act was declared unconstitutional in various portions by the U.S. Supreme Court over the years, but it was not fully repealed until 1993.

For example, in United States v. Spector, the Supreme Court declared a portion of the Act unconstitutional. In Aptheker v. Secretary of State, another portion was declared unconstitutional. And in United States v. Robel, yet another portion was declared unconstitutional.

The McCarran-Ferguson Act is a federal law that allows states to regulate insurance companies doing business in that state and to levy a tax on them. This law helps to ensure that insurance companies are operating fairly and in compliance with state regulations.

For example, if an insurance company is operating in California, the state can regulate that company and make sure it is following all of California's insurance laws. The state can also levy a tax on the company to help fund state programs and services.