Mike Ramsey noted yesterday Garrett Epps's generally useful comments on birthright citizenship in the Atlantic, responding to Rand Paul. Epps is right that there was clear evidence that the Fourteenth Amendment's citizenship declaration, which emerged out of the Republicans' meetings between the Senate's initial discussion of the Amendment on May 23, 1866 and its discussion a week later, applied beyond the freedmen. As Wong Kim Ark itself noted, John Conness of California explained the declaration--which applied to anyone subject to the jurisdiction of the United States, going beyond the citizenship declaration of the Civil Rights Act of 1866, which merely applied to those not subject to foreign powers--in terms of its effect on a few people in California who were subject both to the United States and to the emperor of China. Rand Paul is thus wrong to confine the citizenship declaration to the freedmen and also wrong to speak of its "author."
In the constitutional sense, the Fourteenth Amendment's author was a group of groups: the bicameral Congress, together with the bicameral ratifying state legislatures (20 on my view, more on others'). These many individuals spoke collectively only through the constitutional language itself. As I see it, any particular framer's views of constitutional text are not controlling when they are idiosyncratic, i.e., out of line with the meaning conveyed by that text at the time in virtue of the rules of the language in which was written. Even setting aside this theoretical issue aside, we do not know who exactly drafted the language which Jacob Howard introduced to the Senate on May 30. In the intervening week, it was clear that the Republicans had caucused and agreed to add the citizenship declaration and modify sections 2 and 3. Howard introduced the amendments to the Senate, but did not claim to have composed the language himself. Epps is right about all this.
This is not to say, though, that individual congressmen were never described as authors. The Cincinnati Commercial described an August 24, 1866 speech by John Bingham as "The Constitutional Amendment Discussed by its Author" (see page 19 of the collection here). I take this, however, as hyperbole; Bingham was not the author in the constitutional sense of having authority to adopt it, nor did he even compose the words of the citizenship declaration, as he did the rest of Section One (proposing it to the Joint Committee on April 21).
It is also important to correct Epps's serious error in stating that "Howard had not been a member of the Joint Committee; no one regarded him as an 'author' of any part of the amendment." This is wrong; Howard was one of only six senators on the Joint Committee (see page iii here), and, moreover, the one chosen to explain the Fourteenth Amendment to the Senate in the place of chairman William Pitt Fessenden, who was ill, as well as the Senator who presented the Republican caucus's changes a week later. The Amendment was, moreover, actually known at times as the "Howard Amendment." Howard's explanation of the Privileges or Immunities Clause, though not perfectly free from interpretive difficulty, was by far the fullest account in Congress in 1866, and his excellent work on the Recess Appointments Clause (see here) and the nature of congressional reconstruction power (see here) both testify to his very high status among the constitutional lawyers of the time. His views on anything during Reconstruction are never to be lightly disregarded.