Federal prosecutors in Kansas who couldn't obtain a gag order against a strident patient activist later launched a secret grand jury investigation and issued subpoenas against the woman and her advocacy group — moves some argue are nothing more than government retaliation against an outspoken critic.

Siobhan Reynolds has taken her fight to quash the subpoenas and publicize the proceedings against her to the U.S. Supreme Court, which is expected to take up her request to unseal the case Friday.

"Here the Assistant U.S. Attorney sought the subpoenas in question after the district court denied the government's motion to gag. This sequence of facts strongly suggests that the government has issued these subpoenas in direct retaliation for (Reynolds') political advocacy," the libertarian groups Institute of Justice and Reason Foundation argued in a brief filed with the 10th Circuit Court of Appeals.

The Associated Press obtained a copy of the sealed amicus brief after it was anonymously uploaded to the public document-sharing website Scribd last month. Institute of Justice attorney Paul Sherman denied his organization posted the document but confirmed its contents.

Reynolds' subpoena challenge has been sealed in federal district court in Kansas and the appeals court. The 49-year-old Santa Fe, N.M., woman has acknowledged she is a target of a grand jury investigation into a possible conspiracy to obstruct justice. But because grand jury investigations are confidential, there was little public record showing her related subpoena challenge even existed until the Supreme Court agreed last month to release a redacted version of her appeal.

Reynolds, president of the nonprofit Pain Relief Network, championed the defense of Dr. Stephen Schneider and his wife, Linda, who were convicted earlier this year of a moneymaking conspiracy linked to 68 overdose deaths at a Kansas clinic. Schneider was sentenced to 30 years in prison; his wife received 33 years.

Federal prosecutors tried unsuccessfully in 2008 to get the judge overseeing the Schneider case to issue a gag order against Reynolds. In court documents at the time, the government portrayed Reynolds as having a "sycophantic or parasitic relationship" with the couple and claimed she was using the Schneider case to further her group's political agenda.

Reynolds, who believes a federal crackdown on prescription painkillers has left chronic pain patients needlessly suffering, lined up defense lawyers and paid for a highway billboard sign proclaiming: "Dr. Schneider never killed anyone."

About six weeks after the billboard went up, court documents contend Reynolds and her group received subpoenas seeking documents related to the sign, her communications with numerous lawyers, patients, state medical regulators, the Schneiders and their relatives along with financial and telephone records and an advocacy video she made.

The American Civil Liberties Union, which represented Reynolds at the district court level, alleged in court documents posted on its website last year that the subpoenas were obtained by "a frustrated prosecutor seeking to silence a dissenting advocate."

The Reporters Committee for Freedom of the Press also filed an amicus brief Monday asking the Supreme Court to hear Reynolds' case and decide when prosecutors' demand for information could be found to be in less than "good faith."

U.S. attorney's office spokesman Jim Cross said he could not comment on the allegations of retaliation or any documents in the case, citing the secrecy of grand jury testimony. David Sellers, with the U.S. Courts Office of Public Affairs, said protecting those who are investigated is among the reasons for grand jury confidentiality.

In their amicus brief, the libertarian groups argue the subpoenas impeded Reynolds' right to associate because by demanding information that effectively identified Pain Relief Network members, donors and supporters. The subpoena also sought to reveal Reynolds' advocacy strategies to political opponents, the brief argues.

"Through the subpoenas, the Schneider prosecutors — the very government agents whose actions (Reynolds and her group) oppose — effectively receive (the group's) strategies for challenging governmental policies on pain relief treatment," according to the brief.

Reynolds said last week she did not know who posted the sealed brief on Scribd and would not confirm its contents for fear she would violate the court's order.

The AP last week also found an identical copy of the brief on the website of Reason Magazine, which is published by the Reason Foundation. Senior editor Jacob Sullum said he had deleted links to the document last year after being told to do so by an appeals court clerk, but was unaware it remained accessible through search engines.

It has since been entirely deleted, although Sullum said sealing a brief based on publicly available information is highly unusual and "seems totally unjustified."

Reynolds initially refused to turn over subpoenaed materials, costing her and her nonprofit group $39,400 in fines between September and December last year. Faced with imminent jailing after the money ran out, she gave prosecutors the documents weeks before the Schneiders' summer trial began.

"It was deeply terrifying to think that I put myself, my family and my friends in terrible peril all because I exercised my constitutional right to criticize the government publicly," Reynolds said last month. "If you are living in fear of the government, you are not free. I found out I am not free. None of us are."