What is the test for an equal protection challenge to sentencing guidelines for marijuana possession?

We have recently considered similar arguments and rejected them. See Jordan, 964 F.2d at 947 (Guidelines equating one marijuana plant with one kilogram of dried marijuana "does not create evidentiary presumption" but rather "functions only as a measure of culpability for sentencing purposes"); United States v. Belden, 957 F.2d 671, 676 (9th Cir.) (same), cert. denied, 113 S.Ct. 234 (1992); see, e.g., Chapman v. United States, 111 S.Ct. 1919, 1923 (1991) (equal protection challenge to sentencing scheme duplicated due process argument that sentencing scheme was arbitrary). Accordingly, these contentions lack merit. ¹