A reader writes:
You say that the Supreme Court "backed" California's medical marijuana law. That is misleading in that it implies that the Court has considered the merits of the case or the decision below. Denial of cert has absolutely no substantive connotation.
The Wikipedia entry (certiorari) is pretty accurate:
"Conversely, the legal effect of the Supreme Court's denial of a petition for a writ of certiorari is commonly misunderstood as meaning that the Supreme Court approves the decision of a lower court. However, such a denial "imports no expression of opinion upon the merits of the case, as the bar has been told many times." Missouri v. Jenkins, 515 U.S. 70 (1995)."
This is why, after Lawrence v Texas, when the Court declined to review a case allowing a state to ban gay adoption, you can't say that the Court agrees that gay adoption bans are OK. They just decided not to consider the issue yet, probably waiting for a split among Circuits that they can resolve.