Laurence Tribe is a professor of constitutional law at Harvard Law School, and is considered one of the foremost scholars on constitutional law in the country. Theodore Olson served as Assistant Attorney General during the Reagan Administration, and was Solicitor General under George W. Bush. Both men have argued before the Supreme Court multiple times, and they were founding members of, respectively, the American Constitution Society and the Federalist Society. Simply put, these two men are among the most accomplished and respected legal minds in the U.S. Additionally, Tribe is politically liberal whereas Olson is politically conservative.
On March 19, 2008, the two men issued their report. The portion most relevant to the Birthers' claims has been excerpted previously:
"The Constitution does not define the meaning of “natural born Citizen.” The U.S. Supreme Court gives meaning to terms that are not expressly defined in the Constitution by looking to the context in which those terms are used; to statutes enacted by the First Congress...and to the common law at the time of the Founding.... These sources all confirm that the phrase “natural born” includes both birth abroad to parents who were citizens, and birth within a nation’s territory and allegiance....
"If the Panama Canal Zone was sovereign U.S. territory at the time of Senator McCain’s birth, then that fact alone would make him a “natural born” citizen under the well-established principle that “natural born” citizenship includes birth within the territory and allegiance of the United States...Premising “natural born” citizenship on the character of the territory in which one is born is rooted in the common-law understanding that persons born within the British kingdom and under loyalty to the British Crown–including most of the Framers themselves, who were born in the American colonies–were deemed natural born subjects."
Given the stature of Messrs Tribe and Olson, this should, by any measure, be a nail in the coffin of the 'two-citizen-parent' theory of Presidential eligibility. However, it appears that the memo in its entirety is rather hard to come by online. So I present it here, for your reading pleasure:
The Tribe/Olson 'Natural Born Citizen' Memo