Why aren't all issues of civil rights held to strict scrutiny? Given the US' history of discrimination, what's the philosophical justification for placing some identities in the strict scrutiny basket, and others in heightened/rational basis baskets?
This is a very important question. It all comes down to fraud on the part of the US Supreme Court in a series of cases after the 14th Amendment was passed in 1868. The 14th was supposed to protect a broad swath of civil rights but the US Supreme Court pretended not to know what the meaning of "privileges and immunities of US citizenship" is in the opening paragraph of the 14th:
All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the state wherein they reside. No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.
Problem is, the guy who wrote that (John Bingham, a Republican legislator and top civil rights activist in the US after Lincoln died) said exactly where the meaning of "privileges and immunities" could be found - as defined by the US Supreme Court in 1856 in the nasty Dredd Scott case legalizing racism:
For if they [referring to blacks] were so received, and entitled to the privileges and immunities of citizens, it would exempt them from the operation of the special laws and from the police regulations which they considered to be necessary for their own safety. It would give to persons of the negro race, who were recognised as citizens in any one State of the Union, the right to enter every other State whenever they pleased, singly or in companies, without pass or passport, and without obstruction, to sojourn there as long as they pleased, to go where they pleased at every hour of the day or night without molestation, unless they committed some violation of law for which a white man would be punished; and it would give them the full liberty of speech in public and in private upon all subjects upon which its own citizens might speak; to hold public meetings upon political affairs, and to keep and carry arms wherever they went. And all of this would be done in the face of the subject race of the same color, both free and slaves, and inevitably producing discontent and insubordination among them, and endangering the peace and safety of the State.
http://caselaw.lp.findlaw.com/scripts/getcase.pl?court=US&vol=60&invol=393
Note that these listed "privileges and immunities" included basically all of the Bill of Rights including the 2nd Amendment plus some, like the right to "free travel without pass or passport".
The Dredd Scott case was basically the US Supreme Court saying that racism was always a factor in America (up to 1856 at least) and that therefore racist laws were OK. The Civil War (1861-1865) didn't solve this problem. The 14th Amendment was an attempt to write a constitutional amendment to overturn the US Supreme Court and therefore uses the language of Dred Scott to flip it around.
The Supremes didn't take kindly to this and in a series of cases such as Slaughter-House (1872), US v. Cruikshank (1875, final decision in 1876) and many others basically destroyed the whole opening paragraph of the 14th. Burned it to the fucking ground.
It got rebuilt crooked in the 20th century, based on the "due process" clause instead of the "privilege or immunity" portion. The whole idea of "levels of scrutiny" are an artifact of this cockeyed rebuilding process.
For more info, see either or both of the following books:
http://www.amazon.com/The-Bill-Rights-Creation-Reconstruction/dp/0300082770 - gives a good overview of the fraud that the Supreme Court has never come to grips with.
http://www.amazon.com/Day-Freedom-Died-Massacre-Reconstruction/dp/0805089225/ref=sr_1_1?s=books&ie=UTF8&qid=1425676694&sr=1-1&keywords=charles+%22the+day+freedom+died%22 - a more detailed look at the most critical aspect of the fraud, the events surrounding the Colfax Massacre and the Cruikshank decision that resulted.
At various times individual US Supreme Court justices have tried to blow the whistle. Hugo Black's dissent in Adamson (1947) is the most detailed:
http://en.wikisource.org/wiki/Adamson_v._California/Dissent_Black
...but Clarence Thomas of all people went the same place in a concurring dissent in Saenz v. Roe (1999):
"Concurring dissent" means he was OK with the outcome of the case but thought they should have gotten there a different way. In this case California discriminated against US citizens recently arrived in Cali from other US states and this was held to be a violation of their civil rights. Back in 1870 the US Supreme Court said the same thing in Ward v. Maryland, and then in 1872 in Slaughter-House said that the "privileges or immunities" clause of the 14th ONLY protected US citizens against cross-border discrimination. Saenz repeated Ward over 100 years later but Thomas (with Rehnquist agreeing!) said that we should revisit the true meaning of the Privileges and Immunities clause of the 14th.
He was very likely familiar with the arguments Amar and others made on the meaning of the 14th.
Funny thing: the exact quotes from John Bingham cited by Yale law professor Akhil Reed Amar on what the opening paragraph of the 14th was supposed to mean were previously quoted in a 1984 book called "Let Every Man Be Armed" by Stephen Halbrook, a law professor from George Mason. Nobody took Halbrook seriously because he was well known as an NRA lawyer. Amar on the other hand is a major "lefty" and highly regarded as a constitutional lawyer; when HE said there was something to this argument that our rights had been gutted by a racist Supreme Court between 1872 and 1900, it was Big Fucking News[tm]. Amar's book was one of the "GO NOW" signals that started the process of bringing major gun-rights cases to the US Supreme Court, leading to the Heller (2008) and McDonald (2010) decisions...which sadly STILL didn't fix the fraud of 1872-1900.