What happens to a US federal law if it gets declared unconstitutional by a district judge?

Question

I'm researching the case United States v. Handley, and in the case judge James E. Gritzner declares some parts of the law Handley was charged with unconstitutional, however, many cases since then have passed without constitutional challenge or referring to the Handley case, did James only declare 1466A unconstitutional for his own district? does he have the power to declare a law unconstitutional? and why do I see people insist that James' decision extends to the rest of the US even though it clearly doesn't and hasn't?

James L. Arrasmith · Answer

When a federal district judge declares a law unconstitutional, the ruling typically applies only within that judge's jurisdiction, meaning it directly affects only the parties involved in the case and others within that district. The judge does have the power to declare a law unconstitutional, but their decision doesn't automatically extend beyond their district. Other districts and courts can continue to enforce the law unless a higher court, like a federal appellate court or the Supreme Court, upholds the ruling or makes a broader decision. 
 
In the case of *United States v. Handley*, the judge's ruling on the constitutionality of certain parts of the law would only bind within that district unless appealed and affirmed by a higher court. If no other courts challenge or address the same issue, the law might continue to be applied elsewhere as if the ruling never happened. 
 
People might insist that the decision extends to the rest of the U.S. due to misunderstandings about how federal court rulings work or because they believe that such rulings should have broader implications. However, in practice, the ruling is only binding within the specific district unless higher courts take action.

Q: What happens to a US federal law if it gets declared unconstitutional by a district judge?