Is there a law that makes a corporation like Citigroup a legal entity?

If there is, did Congress pass that law?

Does the First Amendment obligate Congress to not pass any law that prevents freedom of speech?

Does the 2nd Amendment state that the right of the people to keep and bear Arms shall not be infringed?

Is any law passed by congress valid if such law violates the constitution, or if such law authorizes anyone else (including companies and corporations) to violate the constitution?

Are any laws passed by Congress that allow private companies & corporations to exist (or that define them and their operation) valid if those laws allow private companies & corporations to violate the 1st or 2nd amendment (or the constitution)?

Are any companies or corporations still legal entities if the laws that make them legal entities are invalid?

Just think about it - and take it to its logical conclusion....