Silvester and Combs, who already owned firearms, claimed the law was unconstitutional when applied to "subsequent purchasers", or persons who already own a gun, have a concealed carry license, or clear a background check in less than 10 days.
The court's action on waiting periods drew an angry dissent from Justice Clarence Thomas, who said his colleagues had turned the right to bear arms into a "constitutional orphan" with less protection than "rights that have no basis in the Constitution", like same-sex marriage.
Justice Clarence Thomas said the court should have taken up the challenge. "But as evidenced by our continued inaction in this area, the Second Amendment is a disfavored right in this Court".
The Supreme Court has not taken up a major firearms case since issuing important gun rulings in 2008 and 2010 that established an individual right to own guns for self-defense.
The appeals court opinion also contends that the waiting period serves as a "cooling off" period "in which weapons purchasers may reconsider, particularly when an impulsive act of violence or self harm may be contemplated".
The Supreme Court has made landmark decisions in the last decade undermining state-level restrictions on gun ownership.
The 9th U.S. Circuit Court of Appeals upheld the law, relying heavily on the state's "cool down" rationale.
"If a lower court treated another right so cavalierly, I have little doubt that this court would intervene", Thomas wrote.
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In between it was a battle, it was nerve-wracking getting back to No. 1, but I was able to manage my nerves and the expectations. Haase made clear he was going to make Federer fight, and broke him in the ninth game and fired an ace to take the set 6-4.
The National Rifle Association and state gun rights advocates argued the law violates the Second Amendment because the criminal misuse of firearms targeted by the APPS is not sufficiently related to the legal acquisition of firearms on which the fee is imposed.
Only eight other states and the District of Columbia have any type of waiting period. Purporting to apply intermediate scrutiny, the Court of Appeals upheld California's 10-day waiting period for firearms based exclusively on its own "common sense".
"If this case involved one of the court's more favored rights, I sincerely doubt we would have denied certiorari", Thomas said.
The United States has among the most lenient gun control laws in the world.
Tuesday is the Supreme Court's first day in session since a gunman walked into Marjory Stoneman Douglas High School in Parkland, Florida and murdered 17 people.
Thomas said he suspected that the Supreme Court would readily hear cases involving potentially unconstitutional waiting periods if they involved abortion, racist publications or police traffic stops. "And the lower courts seem to have gotten the message".
According to court documents, California's "cooling off" period is the second-longest in the country, The Hill reported.
That argument prevailed before the the U.S. District Court for the Eastern District of California, which ruled against the 10-day waiting period in the context of "previous purchasers".