What is the test for making an equal protection claim against a person who does not have a distinguishing characteristic X?

"There is always some difference between the two groups which a law treats in an unequal manner since an equal protection claim necessarily asserts that the law in some way distinguishes between the two groups. Thus, an equal protection claim cannot be resolved by simply observing that the members of group A have distinguishing characteristic X while the members of group B lack this characteristic. The 'similarly situated' prerequisite simply means that an equal protection claim cannot succeed, and does not require further analysis, unless there is some showing that the two groups are sufficiently similar with respect to the purpose of the law in question that some level of scrutiny is required in order to determine whether the distinction is justified." (People v. Nguyen (1997) 54 Cal.App.4th 705, 714, emphasis added.)

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