Here’s a sentence I don’t type very often: Justice Clarence Thomas has a point. It’s time for the federal government, the Olympics and the rest of us to recognize that legalized, recreational marijuana is a reality.

It is here to stay, notwithstanding those, myself included, who have misgivings about whether that is the wisest course. When 18 states and D.C. have legalized it for recreational use, continuing to put marijuana in the same category of dangerous and illegal drugs as heroin, ecstasy and LSD makes little sense.

So are rules that punish athletes such as Sha’Carri Richardson, who lost out on her Olympic dreams this summer when she tested positive for THC and acknowledged smoking marijuana after her mother’s death.

So, for the matter, is President Biden administration’s move to fire some staffers and not bring on others because of too much and too recent marijuana use. The administration is constrained by rules for granting security clearances and more permissive than its predecessors, but, come on, this is 2021.

I’d prefer not to be making this argument. Seven years ago, when recreational marijuana was legal in just one state and about to be allowed in another, I wrote a column that bemoaned the trend (largely because of fears about teenage use) while recognizing its inevitability.

But here we are. Like Justice Thomas, I think it’s time to recognize reality.

Thomas made that point late last month when the court declined to hear an appeal by a Colorado medical-marijuana dispensary. Such businesses are permitted under state law; for its part, the federal government has essentially said it won’t insert itself into states’ decisions and prosecute marijuana establishments for violating the Controlled Substances Act in places where such activity is legal.

Sensible enough, but such business still operate under significant logistical and financial disadvantages. In calculating their taxes, for example, ordinary retail enterprises are allowed to deduct both the costs of the goods that they sell and other ordinary business expenses, such as rent and salaries. But under the federal tax code, businesses that deal in controlled substances that are illegal under federal law may only deduct the cost of the goods that they sell, not other expenses.

And as Thomas observed, “this disjuncture between the government’s recent laissez-faire policies on marijuana and the actual operation of specific laws is not limited to the tax context.” Many marijuana businesses have to operate in cash because federal law prohibits many financial institutions from taking deposits from businesses whose fundamental financial plan involves violating federal law.

“Once comprehensive, the federal government’s current approach is a half-in, half-out regime that simultaneously tolerates and forbids local use of marijuana,” Thomas wrote. “This contradictory and unstable state of affairs strains basic principles of federalism and conceals traps for the unwary.”

Including Richardson, the champion sprinter who was suspended from competing for 30 days and removed from the Olympics roster of USA Track and Field (USATF) for smoking a substance that is banned by the World Anti-Doping Agency but perfectly legal in Oregon, where she smoked it.

Yes, Richardson knew that she was breaking the rules and — to her credit — didn’t bellyache about the consequences of her actions. “I know what I’m supposed to do and what I’m allowed not to do, and I still made that decision,” she told Savannah Guthrie on NBC’s “Today” show.

Yes, rules are rules, as everyone from Biden to Olympic gold medalist Dominique Dawes has noted. But that doesn’t answer whether it makes sense to apply the rule in this circumstance, at this stage.

Indeed, this is a rule that has outlived its usefulness and whose enforcement in this situation benefits no one. It’s hard to imagine who would be harmed — an athlete who had to refrain from getting high? — if Richardson were given a pass.

But USATF and its Olympics buddies aren’t the only ones who have yet to catch up. Despite changing state laws and public attitudes — 60 percent of Americans support legalizing both medical and recreational marijuana, and another 31 percent favor marijuana for medical use only — numerous employers require drug-testing for new hires and include marijuana among the tested substances. This includes The Post, although The Post has the justification of having some employees who operate printing presses and other dangerous machinery.

The Biden administration’s stance encapsulates this changing reality. A March memo from the Office of Personnel Management makes clear that recent use isn’t automatically disqualifying, noting that a “commitment to not use marijuana going forward may represent evidence of rehabilitation which may be mitigating, even in cases of recent use.” Good, but really, rehabilitation? What is this, “Reefer Madness”?

Thomas’s underlying project, by the way, isn’t marijuana-related. He wants to rein in federal power. In 2005, in Gonzales v. Raich, Thomas dissented when the court ruled that the federal power to regulate interstate commerce could prevent two California women from growing or using marijuana solely for their own medicinal use, legal under state law. Then there were nine states that authorized medical marijuana, and none that permitted recreational use; now there are 36 and 18, respectively.

Prediction: in several years, all this is going to look awfully quaint. The “half-in, half-out regime” of which Thomas complained will be gone, and it will be, pardon the phrase, high time.

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