That's not how this works. The court operates under the rule of stare decsis which would already make this a tough hill to climb. Even more, the line of reasoning in the decision agreeing to federal restriction of in-state marijuana sales goes all the way back to the great depression and is really unlikely to be overturned in just over a decade since it was decided last time.
> the court operates under the rule of stare decsis
Yes and no. If you have a decision on one set of facts made on one basis just come up with another set of facts and another basis where you can get a opposing result without necessary logical conflict and you are all good.
The rat's nest of federal law and prior opinions makes this trivial, so at the end of the day, all legal opinions are arbitrary, and the only actual basis for any decision is whether or not it serves the interests of the court, which outside of the pet peeves, biases, and corruptions of individual judges, consists mostly of the perpetuation of the institution.
The SC's power is rooted in the federal government, and it is stacked with statist/corporatist hacks, so it will always have a preference for extending federal power, but that instinct must be tempered by the threat of an over-extension which reveals the inherent weakness of their position.
Making a move against a majority of the states now, on a subject where popular opinion is clearly against them, and with an all time low level of trust and respect for the federal government would definitely not be desirable.
Normally they could just refuse to hear appeals, but the 9th circuit is in a pretty feisty mood these days so I wouldn't be too surprised if they sided with the states, which would then force the SC to either let their ruling stand, or expose themselves directly on the issue.
Either way, they either let the states keep this going, or they piss off a lot of people, and either way is bad for them and good for the states.
If Rohrabacher-Farr doesn't expire, the states will challenge the action as a violation of federal statute (where they've won before against the Feds trying to narrowly interpret Rohrabacher-Farr) rather than launching a Constitutional challenge of on grounds where there is crystal clear Supreme Court precedent against them, and little reason to believe the Court has moved in their favor.
Even if they also raise the Constitutional argument, a Court that fears public opinion as much as you suggest would likely take the less precedent-disturbing approach to the popular result by resting a decision on Rohrabacher-Farr (even if that took a somewhat expansive interpretation of that prohibition on DoJ use of funds) rather than overturning Gonzalez v. Raich.
