WASHINGTON – A federal appeals court Tuesday accused the Internal Revenue Service of stonewalling the release of lists of tax-exempt organizations targeted for political scrutiny, scolding the tax agency for compounding an offense by continuing to fight disclosure.

The judges ordered the IRS to quickly turn over the full list of groups it targeted so that a class-action lawsuit, filed by the NorCal Tea Party Patriots, can proceed. The judges also accused the Justice Department lawyers, who are representing the IRS in the case, of acting in bad faith and compounding its violation of the law in the first place.

"Among the most serious allegations a federal court can address are that an executive agency has targeted citizens for mistreatment based on their political views," wrote Judge Raymond M. Kethledge in a unanimous decision. "No citizen -- Republican or Democrat, socialist or libertarian -- should be targeted or even have to fear being targeted on those grounds. Yet those are the grounds on which the plaintiffs allege they were mistreated by the IRS here. The allegations are substantial: most are drawn from findings made by the Treasury Department's own inspector general for tax administration. Those findings include that the IRS used political criteria to round up applications for tax-exempt status filed by so-called tea-party groups; that the IRS often took four times as long to process tea-party applications as other applications; and that the IRS served tea-party applicants with crushing demands for what the Inspector General called "unnecessary information."

The case stems from the IRS' decision in 2010 to begin subjecting tea party and conservative groups to intrusive scrutiny when they applied for nonprofit status.

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The IRS has issued an apology, blaming mistakes by low-level employees. Yet it fought for more than five years demands for full disclosure and documents sought by tea party groups.

Kethledge wrote in his opinion that the IRS' conduct since the original offense has "only compounded the conduct" that gave rise to complaint in the first place.

"The lawsuit has progressed as slowly as the underlying applications themselves: at every turn the IRS has resisted the plaintiffs' requests for information regarding the IRS's treatment of the plaintiff class, eventually to the open frustration of the district court," wrote Kethledge. "At issue here are IRS 'Be On the Lookout' lists of organizations allegedly targeted for unfavorable treatment because of their political beliefs. Those organizations in turn make up the plaintiff class. The district court ordered production of those lists, and did so again over an IRS motion to reconsider. Yet, almost a year later, the IRS still has not complied with the court's orders. Instead the IRS now seeks from this court a writ of mandamus, an extraordinary remedy reserved to correct only the clearest abuses of power by a district court. We deny the petition."

The court wrote in some detail about IRS selective and intrusive demands for information from the aggrieved groups.

"In 2010, the IRS began to pay unusual attention to 501(c) applications from groups with certain political affiliations," Kethledge wrote. "As found by the inspector general, the IRS 'developed and used inappropriate criteria to identify applications from organizations with 'Tea Party' in their names. ... As to the policy positions, the IRS gave heightened scrutiny to organizations concerned with 'government spending, government debt or taxes,' lobbying to 'make America a better place to live or 'criticiz[ing] how the country is being run.'"

The court found the IRS kept this inappropriate criteria in place for more than 18 months and that when applications were wrongly flagged they were passed on to a team of specialists where applicants "experienced significant delays and requests for unnecessary information," according to the IRS' own inspector general.

While the standard time for processing applications was 122 days beginning in 2012, "the average time a potential political case ... was open as of December 17, 2012, was 574 calendar days," while some cases dragged on for four years.

The Justice Department declined to comment on the decision.