Your initial post was to the effect that Holder (or those at the Department of Justice who actually drafted the letter in question) don't know the difference between the 5th and 14th Amendments because the letter references "equal protection" in connection with the 5th Amendment.
That there is no "express" Equal Protection Clause in the Fifth Amendment goes without saying. It should also go without saying that, right or wrong, the Supreme Court long ago in fact found that there is an "equal protection component" to the 5th Amendment. Again, that may be correct as a matter of constitutional jurisprudence, or it may be wrong. But that is what the Court has found.
Given this, the DOJ letter hardly provides support for your assertion that Holder, et al. have revealed some gross misunderstanding of the Constitution.
Many, if not most, lawyers will probably agree with you, and with Holder, on this point.
But I’m thinking most regular folks, who have to rely solely on what the actual words of the Constitution say, will agree with me. (After all, the Fourteenth Amendment explicitly requires “equal protection,” while the Fifth makes no express mention of it.)
In fact, the posts already on this thread are an illustration of the point.
Lawyers in America today are overwhelmingly caught up in straining at the gnats of the doctrines that have been built up around the law, even if the words of the Constitution don’t support them, while at the same time swallowing the camel by ignoring most of the important clear imperative requirements of what the document actually says and means.
Which raises an even more important point: If we all agree, which we apparently do, that the Fourteenth Amendment requires that the states provide for the equal protection of the laws for all persons in their jurisdiction, and that the Fifth Amendment requires the national government to do the same, why are they not providing equal protection to all persons? Why are thousands of little persons continuing to be butchered in this country every single day?
Why does one subclass of immoral person have a “right” to do what our civilization has always considered to be an abominable act, while another subclass of persons don’t even have the most fundamental protection for the most important thing any human being has, their own life?
Well, completely beside the point of whether he misunderstands equal protection, and which Amendment may or may not require it, he, and they, do grossly misunderstand the Constitution. Otherwise, they wouldn't be turning basic right and wrong on its head and claiming there is a "right" to do wrong.
Ironically, apart from all the legal mumbo-jumbo that surrounds the question of incorporation, I think the Fifth Amendment was always intended to protect the God-given and therefore unalienable rights of all persons. And that obligation has always existed for all human governments, preceding the existence of a Fifth, or a Fourteenth Amendment - or a U.S. Constitution.
In fact, that's the cornerstone principle of our republic.
"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness. That to secure these rights, governments are instituted among men..."