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.