RICHMOND, Va. — A privacy advocate filed a lawsuit yesterday challenging a new Virginia law prohibiting citizens from disseminating Social Security numbers that anyone can legally obtain from government Web sites.

Betty “BJ” Ostergren claims the statute, scheduled to take effect July 1, is unconstitutional because it violates the First Amendment’s protection of freedom of speech. She asked the federal court in Richmond to block enforcement of the law until the case is decided.

Ostergren has gleaned from online government records the Social Security numbers of many prominent people — Jeb Bush, Colin Powell, Kelly Ripa and Joe Namath among them — and posted them on her own Web site to demonstrate government’s failure to protect individuals’ privacy.

She says her efforts have helped persuade officials in some states to remove personal information from online records. Virginia’s General Assembly, however, responded by unanimously passing legislation making Ostergren’s tactics illegal and punishable by a $2,500 civil penalty.

“I think the legislature, to have targeted me instead of fixing the real problem, which is the Circuit Court clerks leaving Social Security numbers on records that are now going to be available in people’s homes, was wrong,” Ostergren said in a telephone interview. “They did target me, because I’m the only one in the state doing it, and I’m not going to stand for it. I’m not going to lose my First Amendment rights.”

The lawsuit names Attorney General Robert F. McDonnell as the sole defendant. McDonnell spokesman David Clementson said lawyers in the office were reviewing the lawsuit and had no immediate comment.

State Sen. R. Edward Houck, D-Spotsylvania and sponsor of the legislation, did not immediately respond to phone and e-mail messages seeking comment. Houck said after Gov. Timothy M. Kaine signed the measure in March that he could see no purpose in anyone distributing a Social Security number found online.

The American Civil Liberties Union supports privacy rights but believes legislators took the wrong approach in targeting individuals like Ostergren, state ACLU executive director Kent Willis said. The ACLU is representing Ostergren in the lawsuit.

“The primary purpose of this law seems to be to mask the fact that Virginia legislators have failed to prevent Social Security numbers from being placed on Web sites,” Willis said. “Rather than fixing the law and requiring they be redacted, they punish individuals who take the records and use them.”

State law already prohibits individuals from disclosing Social Security numbers obtained from private sources. However, millions of public records ranging from land deeds to divorce decrees are available online in Virginia containing Social Security numbers and other private information.

“If the government is going to put a record on a Web site for the public to view, it can’t prevent the public from disseminating that information,” Willis said.