A nonprofit advocacy group representing New Jersey charter schools filed an ethics complaint this week accusing a Rutgers University professor of abusing her title and improperly using her university affiliation to lobby against charter schools.

Julia Sass Rubin, an associate professor at the Edward J. Bloustein School of Planning and Public Policy, denied the accusations, describing them as an attack on academic freedom and an attempt to silence her.

The New Jersey Charter Schools Association, a nonprofit group that advocates for charters, has long butted heads with Save Our Schools New Jersey (SOSNJ), a group Rubin founded to support traditional public schools and that has criticized charters.

The pro-charter school group wrote in its complaint to the state Ethics Commission that it was filing its complaint because of a paper Rubin published in October titled "New Jersey Charter Schools: A Data-Driven View, Part I." The paper, published on the Save Our Schools website, was coauthored with doctoral student Mark Weber, and he and Rubin identified themselves by their Rutgers affiliations.

"The paper's conclusion and recommendations are identical to - and clearly intended to provide the appearance of legitimate academic support for - the lobbying positions that Dr. Rubin and SOSNJ have zealously promoted for years," the Charter Schools Association wrote in its complaint.

The association also cites times in which Rubin has used her academic title - testifying before the Legislature and writing opinion pieces - to make statements in line with Save Our Schools positions.

"SOSNJ capitalizes on Dr. Rubin's affiliation with Rutgers, which lends credibility to SOSNJ's lobbying efforts and political agenda," the Charter Schools Association wrote.

The New Jersey State Ethics Commission declined to comment on the complaint, following a policy of neither confirming nor denying investigations. A spokesman for Rutgers declined to comment on the complaint, calling it a personnel issue.

Rubin said her work was protected as free speech and under principles of academic freedom.

"It's a very disturbing infringement on freedom of speech," Rubin said in an interview. "It's meant to shut me up, and it's meant to try to sully my reputation. I think it's deeply disturbing."

Rubin questioned the Charter School Association's integrity in the way it quoted Rutgers' policy on lobbying. The university's policy describes "lobbying communication" as "any in-person or indirect unsolicited communication made on behalf of Rutgers, including oral, written, or electronic communication, to influence government officials including, but not limited to: an appropriations request, action on legislation, rules, regulations, contracts, nominations, or any other governmental program or policy."

The complaint includes this definition but uses an ellipsis in place of "made on behalf of Rutgers," an alteration Rubin called "disturbing in terms of their integrity."

Michael P. Turner, a spokesman for the association, said Rubin's identifying herself as a professor rather than as chair of Save Our Schools gave the appearance of speaking on behalf of the university.

"She never clearly delineated on whose behalf she was coming there to speak," he said of her appearances before the Legislature since 2011.

In its complaint, the association calls on the Ethics Commission to direct Rubin to stop using her Rutgers title "in any activity on behalf of or coordinated in any way with SOSNJ."

Rubin said she would continue to speak out.

"If you can silence academics that easily, then basically you have no freedom of speech for a lot of people who are often the only ones who can speak up," Rubin said. "And that's the whole idea of an academic institution, is, you have the ability to speak. No one assumes you're speaking for the university."