Supreme Court denies certiorari, declining to review whether the IRS violated the Administrative Procedure Act in interpreting tax regulation regarding cost-sharing arrangements. The U.S. Chamber filed an amicus brief supporting the cert. petition. When this case was before the Ninth Circuit, the U.S. Chamber filed amicus briefs at the initial panel stage, the second panel stage after the court sua sponte vacated the first panel’s opinion, and again in support of rehearing after the second panel’s opinion.