Gun rights advocates have created a cottage industry out of suing to overturn the gun control laws of states and localities - and with real success, including suits against the District and Chicago that have led to landmark Supreme Court rulings. But targeting Texas, home to some of the most gun-friendly laws in the country?

That is exactly what the National Rifle Association has done in challenging a long-standing Texas law that allows only those above the age of 21 to carry concealed weapons. The only exceptions involve 18- to 20-year-olds who are military veterans or who are on active duty.

The NRA and James D'Cruz, an 18-year-old Lubbock resident, sued the state in federal court, arguing that the law unconstitutionally restricts the teenager's right to keep and bear arms. Keep in mind that Texas allows Mr. D'Cruz to own a gun and keep it in his home and car; he just may not carry it around with him until he turns 21.

Mr. D'Cruz argues that he needs a gun for protection when "shopping in certain parts of the city." A lawyer for Mr. D'Cruz explains that the Wal-Mart in Lubbock is in a bad part of town. There's another reason why Mr. D'Cruz says he wants a concealed-carry permit, according to his complaint: "Mr. D'Cruz has a 29-year-old brother and military friends who share his interest in firearms safety and collecting. He would like to transport to, and carry a handgun in, their homes so that they might jointly discuss and demonstrate proper cleaning and safety practices with the handgun."

Mr. D'Cruz filed a separate suit against a federal law that prohibits licensed gun dealers from selling a handgun to anyone who is not yet 21.

Law-abiding adults, the Supreme Court has ruled, have a constitutional right to keep and bear arms. But that right is not unlimited, as the court made clear by citing several restrictions - including prohibitions against carrying weapons into a courthouse or a school - that would withstand legal challenge. The Texas and federal laws fit into this category. Eighteen-year-olds can and do fight for their country. And they are able in many instances to vote and partake of the full rights enjoyed by much older citizens. But there is nothing unconstitutional about the state or federal government determining that a few more years of maturity - and the discipline and wisdom that hopefully come with such age - are needed before such a youngster is allowed to carry a lethal weapon on the streets. It takes some kind of gumption - or blind ideological fervor - to challenge such reasonable limitations.