A federal judge has dealt a defeat to a conservative legal group’s challenge to what the group claims are unconstitutional speech restrictions imposed as part of the Medicare prescription drug program for senior citizens.

Rules issued before the drug program took effect last year limit the ability of pharmacies and nursing homes to give patients information comparing various drug plans. The regulations also set up a complex procedure to seek government pre-approval of marketing materials for the plans.

A pro-business advocacy group, the Washington Legal Foundation, argued in a lawsuit that the procedures violated the First Amendment and amounted to an effort to censor advice nursing homes and pharmacies give to their patients.

Yesterday, Judge Rosemary Collyer refused the group’s request for an injunction to block the regulations. She concluded that the foundation lacked legal standing to sue. The foundation’s “purpose does not appear to be germane to the interests of the Medicare Part D subscribers it wishes to represent here,” the judge wrote.

The group’s chief counsel, Richard Samp, said yesterday that it would seek to amend its lawsuit to add several individual Medicare enrollees as plaintiffs. Asked why the providers directly subject to the rules had not filed suit, Mr. Samp said, “There are a growing number of doctors, nurses, nursing homes, and pharmacies outraged by the policy. My guess is many people see a downside to filing a lawsuit against federal regulators from whom you need regulatory approval.”

“We don’t have that problem,” he added.

Government lawyers argued that the marketing restrictions are narrowly tailored and were designed to address possible conflicts of interest that could arise because pharmacies and nursing homes could benefit financially from a patient’s choice of plan.