The ad, titled "Who knows?" focuses on whether Ms. Warren sought to parlay unproven claims to native American heritage into career advancement as a law professor.
The two candidates are locked in a tight race. Senator Brown began pressing the issue months ago, after the matter emerged in local news reports. But this week's ad is Brown's first on the issue.
Brown's advertisement shows news footage of reporters talking about Warren's claim to Cherokee ancestry in her Oklahoma family. Then a reporter asks Warren: “Is there anything else that’s going to come out about you that we don’t already know?” The Democrat laughs in response. “You know, I don’t think so, but who knows?”
The ad follows a public debate last week, in which Brown raised the issue face to face with Warren, arguing that serving in the Senate requires passing a test of "character." He said she clearly is not native American – an apparent reference both to her white skin and to a lack of evidence to prove native American ties.
Warren has responded to Brown's ad with her own 30-second video, speaking directly to the camera with this message: "I never asked for and never got any benefit because of my heritage."
A good many voters in the state agree with the view that she didn't benefit. Others disagree, however. And Warren's critics argue the important question is not whether she benefited, but whether career advancement was her motive.
Here is what has come out so far through the political campaigns and through media reports.
1. Warren listed herself as a minority. The Association of American Law Schools (AALS) directory included, as of its 1986-87 edition, a list of "minority law teachers." Warren, then at the University of Texas, was on the list. Moving to the University of Pennsylvania the next year, she continued to be on the minority list through the directory's 1994-95 edition. The later years of her listing coincided with her recruitment by Harvard Law School, initially as a visiting professor.
2. Harvard was under pressure to diversify its faculty. Warren's listing came at a time when law schools around the country faced pressure from minority advocates to show greater diversity on their faculty, in race as well as gender. In one 1992 incident, students staged a sit-in in the office of the Law School dean to push for greater faculty diversity.
A sign of the times: The AALS list of minority law professors grew from four pages in length in 1986-87 to seven pages by the mid-1990s.
3. Harvard hired her, and she was viewed as boosting racial diversity. The Boston Herald cited a 1996 Harvard Crimson article in which a law school spokesman listed "one native American" as part of a diverse faculty, a reference to Warren. Similarly, the Crimson in 1998 referred to Warren as "the first woman with a minority background to be tenured" at the law school, the Herald said.
The Boston Globe reported that in 1999, Harvard published an affirmative action report that lists a native American professor at the law school, specifying that the individual is female.
Before Warren arrived full time at Harvard, some of the people leading the diversity push apparently viewed Warren as a minority. A 1993 issue of the Harvard Women’s Law Journal listed her among "women of color" in legal academia.
4. Full details about her hiring have not been made public. Warren's campaign has released statements from some people involved in the hiring committees that recruited her at Harvard and the University of Pennsylvania. Robert Clark, former dean of the Harvard Law School, said "her Native American heritage was not a factor in the discussion or the decision."
But Warren has not asked that Harvard release documents related to her hiring, as Brown has urged her to do. Some important details about her career advancement remain in question.
Warren has said that, in addition to listing herself as a minority in the AALS directory, she claimed minority status with her employers. "At some point after Elizabeth was hired at the University of Pennsylvania and at Harvard, she made officials aware of her Native American heritage because it's true and because she's proud of her background," says a statement on her campaign website.
It is not unusual that information about a new hire's racial identity would be provided after the fact of hiring. Data on group identities are gathered, separate from the hiring process, for tracking an institution's record on affirmative action.
5. Warren doesn't appear to fit Harvard's definition of minority. In one document published in 1997, Harvard published details of its affirmative action plan. It defined a native American as “a person having origins in any of the original peoples of North America and who maintains cultural identification through tribal affiliation or community recognition." The document said this definition is consistent with federal regulations.
Warren has cited family lore of Cherokee and Delaware heritage on her mother's side of the family. But genealogists have not been able to confirm any ties. Warren is not known to have maintained any cultural affiliation, such as with a tribe.
6. She stopped listing herself as a minority. Warren's listing as a minority teacher in the AALS directory ended with the 1994-95 edition, when she was at the University of Pennsylvania and being recruited by Harvard. Early on in the controversy, Warren said her goal in the minority listing was to meet others with a similar background, and when such social contacts didn't develop she dropped the listing.
The party opted not to have Warren face a primary opponent, and she was given a prominent speaking spot at the Democratic National Convention early this month.
The Scott Brown camp, meanwhile, has stirred up a bit of controversy on its own side this week. Some members of his campaign staff were caught on videotape whooping and making tomahawk motions near a group of Warren supporters, according to local news reports.
"It is certainly something that I don't condone," Brown said on WCVB Tuesday. "It's certainly something that, if I'm aware of it, I'll tell that member to never do it again."
In a separate comment Tuesday, he took the issue back to Warren: "The offensiveness here is the fact that Professor Warren took advantage of a claim to be somebody, a native American, using that for an advantage.... And then after she attained tenure she unchecked that box."