Thanks for the comments on my first post. I'd like to take up Hans Bader's defense of Cruikshank, because it concisely gets to the heart of the matter: the state action requirement found by the Court in that case.
My book goes into this history in some detail, because it is crucial to understand that this requirement, so evident to some in retrospect, was not immediately perceived by all jurists at the time of the 14th Amendment's ratification.
In 1871, the Fifth Circuit held, in a case called US v. Hall, that the 14th Amendment incorporated the Bill of Rights(through the privileges and immunities clause — Prof. Bader and I agree, I think, that this was a proper interpretation that The Slaughterhouse Cases later muddled).
The facts of Hall, briefly, were that a political meeting of black men in Alabama was attacked by Klansmen, with casualties (all black Republicans) including killed and wounded. The US Attorney charged the Klansmen with conspiring to violate the men's First Amendment rights. The Fifth Circuit upheld the indictment by holding not only that the 14th Amendment incorporated the First Amendment against the states, but also — and crucially — that state inaction, i.e., failure to protect rights, was a form of state action. This was not the holding of Judge William B. Woods, the Fifth Circuit judge of the time alone: it was suggested to him privately in a letter from none other than Justice Joseph P. Bradley.
Thus, as of the Colfax Massacre, the law of the land was Hall, which stoo for the proposition that the 14th Amendment could be a shield against anarchy as well as (state) tyranny. This made sense in the context of the time: a contrary ruling would have enabled the Klan to conquer the South simply by creating a state of terror and ungovernability. The Slaughterhouse Cases would modify that considerably, of course; interestingly, Slaughterhouse was decided on April 15, 1873--two days after the Massacre.
The key ruling in Cruikshank was not so much the Supreme Court's 1876 decision as Bradley's 1874 ruling as circuit justice for the 5th Circuit, which overturned both Hall — and, of course, Bradley's own previous (private) view.
In my judgment, this about-face was not dictated by Slaughterhouse, which, even as it reduced the privileges or immunities clause of the 14th Amendment, left open the possibility that assembly, gun possession and due process rights might be part of protected "federal" POI. Furthermore, Slaughterhouse dealt with state action, par excellence: a statute setting up a regulated abbatoir that all butchers must use. It did not necessarily cover the anarchic situation contemplated by Hall — and presented by the Colfax incident.
What happened in between to change Bradley's mind? Remember that he dissented in Slaughterhouse, so you might have expected him to interpret it as narrowly as possible while riding circuit in Cruikshank. Instead, he wielded it aggressively against the federal prosecution.
I would argue that two things — neither of them legal — dictated Bradley's response.
1. Politics. The 1872 election had precipitated a split in Bradley's Republican party, between those who supported Grant's relatively aggressive use of federal power to stifle Klan violence in the South and those who thought it was an unconstitutional fool's errand. Bradley clearly leaned in the latter direction, as did several other Republicans on the Supreme Court at the time.
2. Race. Bradley had never been an abolitionist and in fact had a long history as a pro-South, pro-slavery Northerner. This changed briefly during and shortly after the Civil War, but by 1874, he was thoroughly frustrated with what he saw as the excesses of black-supported "carpetbagger" governments in the South. His dissent in Slaughterhouse was predicated, in part, on his wildly exaggerated belief that the Louisiana slaughterhouse statute was some kind of corrupt carpetbagger imposition, when in fact it was a moderate and sensible public health measure. In Cruikshank, when black lives and not white Southerners' sensibilities were at stake, his judgments changed accordingly.
This may seem unduly harsh as an assessment of Bradley's motivations, but I think it's accurate (at least that's how I argue it in my book). It helps to account for his seeming enthusiasm for a broad view of the 14th Amendment in Slaughterhouse, and his ultra-narrow view in Cruikshank.
The 14th Amendment, by the way, was not the only basis for the federal indictment in Colfax — or for the later decisions by Bradley (and the entire Supreme Court) which struck the indictment down. The 13th and 15th Amendments, and statutes derived from them also played a role. Even if Cruikshank was rightly decided on the 14th, the court might still have upheld the charges on other grounds. But I'll go into that more in a subsequent post.