Don't read this post unless you're sincerely curious about this shit, otherwise it's boring.
Broadly speaking, equal protection claims involve a challenge to laws that allocate benefits or impose burdens on a defined class of individuals (While it is possible to have a "class of one", see: Village of Willowbrook v. Olech, laws generally define classes more broadly).The plaintiff in an equal protection case claims that the government has drawn the line between the favored and disfavored groups in an impermissible place. But the fact of treating individuals differently cannot ivnariably give rise to an equal protection violation: such an approach would make government impossible, since nearly all government actions classify individuals. For example, a law that sets the driving age at sixteen treats fifteen-year-olds and seventeen-year olds differently, classifying on the basis of age, while a deciision to set the passing score for the bar examination at 75 treats applicants who scored 74 differently from those who scored 76, classifying on the basis of test performance. Thus, the real question in equal protection cases involves deciding whether, under particular circumstances, a challenged classification is permissible.
The court approaches this with three primary guiding questions: 1) How has the government defined the group being benefited or burdened (the question of "means")? 2) What is the goal the government is persuing (the question of "ends")? 3) Is there a sufficient connection between the means the government is using and the ends it is pursuing (the question of "fit" or "nexus")?
When analyzing it, the court doesn't do it blindly. They choose from certain "tiers" of review, more commonly called 'standards of review'. Normally, a reviewing court asks whether the line the government has drawn is related in a discernible way to the achievement of a permissible government purpose. This form of scrutiny, called rationality review, is generally quite deferential. But when the line that the government has drawn is constitutionally troublesome, the standard of review shoots up to being very strict. Constitutionally troubling lines are the protected classes: race, sex, etc.
The equal protections clause does state "equally". What does it mean to treat two people, or two groups of people, "equally" for purposes of the equal protections clause? COnsider, for example, whether each of the following hypothetical employment rules for the New York Transit Authority provides for equal treatment:
a) No position shall be filled by a woman
b) no position shall be filled by a person weighing less than 175 poudns
c) no position shall be filled by a person without a high school diploma
d) all positions shall be filled by lot
e) all persons applying for any position shall be hired
In a trivial sense, each of these rules provides for equal treatment. Under each of them, every applicant is equally subject to the same criteria. Thus, under rule C, all applicants are equally subject to the requirement of a high school diploma, and under rule A, all applicants are equally subject to the requirement that they be male. Indeed, ALL rules, if they are applied as written, provide for equality in this sense. Thus, under rule B, it would violate equality of treatment for the Transit AUthority to hire one individual who weighs 150 pounds, while refusing to hire another individual on the grounds that she weighs less than 175 pounds.
In a similar trivial sense, each of the hypothetical employment rules denies equal treatment. Under each of them, some people are denied a benefit that is granted to others. Inequality in this sense is also inescapable. Even rule E, which requires hiring all people who apply for the position, discriminates against the class of people who did not apply for the position.
These examples illustrate another difficulty with the concept of equality. Providing similar treatment to two groups will not result in equal treatment if the groups are not similarly situated. Rule B, for example, provides similar treatment to all applicants. They cannot weigh less than 175 pounds. But in one obvious sense, the rule does not provide equal treatment because applicants are not similarly situated with respect to the rule. SImilarly, rule D gives everyone an equal chance to win a job in a lottery. But even if the lottery is fairly conducted, the decision to use a loterry might generate complaints if the winner is less qualified for the job or less in need of it or less "deserving" of it than the loser.
Equality might be measured with respect to formal treatment, but it raises an important question about the perspective from which equality is measured. As long as each individual is subjected to the same selection regime, the requirement of equality is satisfied. Or equality might be measured with respect to outcomes: as long as each individual obtains the same level of benefits equality has been achieved. Suppose that all subway mechanics need protective helmets. Suppose, fuyrther, that some workers can use stock helmets that cost $100, but that other workers, either because of the size of their heads or because they wish to wear religious head coverings under their helmets, must obtain custom-made helmets that cost $200. Does equality require, prohibit, or permit the Transit Authority to provide each worker with the same helmet allowance?
The equal protection clause, in determining what to treat equally, usually defers to the rest of the constitution. So, for example, the first amendment protects the free exercise of religion. Thus, if a state denied a generally available government benefit - drivers' licenses - to a class of people because of their individual religious beliefs, the law would be unconstitutional under the equal protections clause.
The original intent of the fourteenth amendment was to protect African Americans from discrimination on the basis of race. Note that the words do not provide for special treatment of racial classification (compared with the fifteenth amendment. Race, though, is viewed under the strict scrunity view when brough up under the equal protections clause. Specifically, it is viewed as if race is rarely, if ever, relevant to any legitimate governmental purpose. So a state's justification requirement for legislation where race is the primary focus has to deal with an extreme burden of proof.
For the best, succint, simple look at how the 14th is expected to work with regards to the judicial branch,
Carolene Products is the place to look. It's a case about milk, and the case itself really doesn't cover it at all. It's specifically under a footnote, which is funny, but it's the general description of the 14th's doctrine. Footnote 4:
There may be narrower scope for operation of the presumption of constitutionality when legislation appears on its face to be within a specific prohibition of the Constitution, such as those of the first ten amendments, which are deemed equally specific when held to be embraced within the Fourteenth. See Stromberg v. California, 283 U. S. 359, 283 U. S. 369-370; Lovell v. Griffin, 303 U. S. 444, 303 U. S. 452.
It is unnecessary to consider now whether legislation which restricts those political processes which can ordinarily be expected to bring about repeal of undesirable legislation is to be subjected to more exacting judicial scrutiny under the general prohibitions of the Fourteenth Amendment than are most other types of legislation. On restrictions upon the right to vote, see Nixon v. Herndon, 273 U. S. 536; Nixon v. Condon, 286 U. S. 73; on restraints upon the dissemination of information, see Near v. Minnesota ex rel. Olson, 283 U. S. 697, 283 U. S. 713-714, 283 U. S. 718-720, 283 U. S. 722; Grosjean v. American Press Co., 297 U. S. 233; Lovell v. Griffin, supra; on interferences with political organizations, see Stromberg v. California, supra, 283 U. S. 369; Fiske v. Kansas, 274 U. S. 380; Whitney v. California, 274 U. S. 357, 274 U. S. 373-378; Herndon v. Lowry, 301 U. S. 242, and see Holmes, J., in Gitlow v. New York, 268 U. S. 652, 268 U. S. 673; as to prohibition of peaceable assembly, see De Jonge v. Oregon, 299 U. S. 353, 299 U. S. 365.
Nor need we enquire whether similar considerations enter into the review of statutes directed at particular religious, Pierce v. Society of Sisters, 268 U. S. 510, or national, Meyer v. Nebraska, 262 U. S. 390; Bartels v. Iowa, 262 U. S. 404; Farrington v. Tokushige, 273 U. S. 284, or racial minorities, Nixon v. Herndon, supra; Nixon v. Condon, supra: whether prejudice against discrete and insular minorities may be a special condition, which tends seriously to curtail the operation of those political processes ordinarily to be relied upon to protect minorities, and which may call for a correspondingly more searching judicial inquiry. Compare 17 U. S. Maryland, 4 Wheat. 316, 17 U. S. 428; South Carolina v. Barnwell Bros., 303 U. S. 177, 303 U. S. 184, n 2, and cases cited.
If you read all this there's something wrong with you.