Tuolumne County Sheriff Jim Mele made waves last week when he joined a handful of county sheriffs vowing to not enforce "unconstitutional" federal gun rules, a preemptive move in the national gun control debate.

Question is: Can he do that? That is, not enforce a federal gun law?

According to constitutional law experts, the answer is yes.

The Supremacy Clause of the U.S. Constitution says federal law is supreme. However, the 10th Amendment and a handful of U.S. Supreme Court decisions have elevated the issue of state sovereignty, experts say.

Tuolumne County Sheriff Jim Mele entered the fray when he addressed a letter to President Barack Obama on Tuesday, saying he wouldn't take guns away from law-abiding citizens.

There is currently no plan to take guns from citizens, though some gun-control proposals, spurred by mass shootings in Connecticut and Colorado last year, would ban assault-type rifles and high-capacity clips, and tighten gun registration requirements nationally.

"I believe that every law abiding adult citizen has the right to own, possess, use, keep and bear firearms," Mele wrote.

"… we will continue our fight for that which is right and that, is to protect and to serve the citizens of this County. I and the young hero's that serve our community, will not take guns from law-abiding citizens who have the right to protect themselves and their families."

Calaveras County Sheriff Gary Kuntz has not issued a formal statement but said in a telephone interview Thursday that he probably would not enforce gun laws if he felt they infringed on citizens' Second Amendment rights.

"There's a certain complication to that," University of California, Berkeley law professor Jesse Choper said. "It's perfectly clear that their conduct of being hostile, if you will, to federal law is violative of the Constitution because federal law is supreme.

"On the other hand, there are decisions that say at least Congress or the executive branch cannot force states to enforce federal laws."

Choper and other legal experts, along with Mele, referenced the Brady Act.

The Brady Handgun Violence Prevention Act, enacted in November 1993, called for background checks on gun purchasers. Because the U.S. Department of Justice hadn'tdeveloped a national computerized background check system when the act became law, local law enforcement agencies were directed to conduct background checks on prospective gun owners within a five-day waiting period.

Seven district courts heard arguments regarding the act, and five of them held that it infringed upon the sovereignty of the states under the 10th Amendment.Many law enforcement officials opposed the statute, including Jay Printz, who was serving as the Ravalli County sheriff in Montana.

The sheriff challenged the act's constitutionality at the U.S. Supreme Court. In the 1997 Printz v. U.S. decision, the Court held that the act violated the 10th Amendment.

Two years earlier, the Court ruled in a separate case - U.S. v. Lopez - that Congress exceeded its powers under the Commerce Clause when it enacted the Gun-Free School Zones Act of 1990. The statute prohibited individuals from possessing firearms in school zones.

A San Antonio high school student, Alfonso Lopez Jr., challenged the act after he was convicted of violating it when he brought a concealed weapon and bullets onto campus.

While local law enforcement agencies do not have to enforce federal law, federal law officials can enter a state and enforce the law on their own, experts said.

The U.S. Forest Service enforces federal laws in the area and the Sheriff's Office cannot interfere with that, Mele said.

"The supremacy of federal law does not carry over to mean that local and state officials have to implement federal law, that just means they can't interfere with federal law officials," UC Davis law professor Vikram Amar said.However, local law enforcement does have to enforce laws imposed by the state.

"The sheriff would be flouting California law by not cooperating," Amar said. "Counties are just units of the state."

Mele said his office doesn't enforce federal laws that contradict California laws, such as marijuana regulations.