Legal Question in Constitutional Law in Maryland

Re: federal statutes

Federal and state statutes coexist. They can and often do address the same matters, which is usually fine unless they are in conflict. Such conflicts are always resolved in favor of the federal statute.

There are also areas in which the federal government has exclusive jurisdiction (for example, bankruptcy or immigration) or has "occupied the field" and thereby invalidated all state laws on the subject -- including those which are consistent with the federal laws.

Relatively few federal statutes apply specifically "to" states. If you are asking whether they can be enforced within states, and the answer is of course they can. Where else would they be enforced?