Court hears Stone aide's case that Mueller probe is invalid

Attorney Paul Kamenar speaks to media as he leaves federal court in Washington, Thursday, Nov. 8, 2018. Judges on a federal appeals court heard argume

Attorney Paul Kamenar speaks to media as he leaves federal court in Washington, Thursday, Nov. 8, 2018. Judges on a federal appeals court heard argume

Attorney Paul Kamenar leaves federal court in Washington, Thursday, Nov. 8, 2018. Judges on a federal appeals court heard arguments from Kamenar and a

Attorney Paul Kamenar leaves federal court in Washington, Thursday, Nov. 8, 2018. Judges on a federal appeals court heard arguments from Kamenar and a

Attorney Paul Kamenar, center, speaks to reporters outside federal court in Washington, Thursday, Nov. 8, 2018, as Peter Flaherty, right, Chairman and

Attorney Paul Kamenar, center, speaks to reporters outside federal court in Washington, Thursday, Nov. 8, 2018, as Peter Flaherty, right, Chairman and

From left, attorney Paul Kamenar, joined by Don Santarelli, center, and chairman of the National Legal Policy Center, Peter Flaherty, speaks to media

From left, attorney Paul Kamenar, joined by Don Santarelli, center, and chairman of the National Legal Policy Center, Peter Flaherty, speaks to media

Attorney Paul Kamenar, left, joined by Chairman of the National Legal Policy Center, Peter Flaherty, speaks to media as they leave federal court in Wa

Attorney Paul Kamenar, left, joined by Chairman of the National Legal Policy Center, Peter Flaherty, speaks to media as they leave federal court in Wa

Attorney Paul Kamenar as he leaves federal court in Washington, Thursday, Nov. 8, 2018. Judges on a federal appeals court heard arguments from Kamenar

Attorney Paul Kamenar as he leaves federal court in Washington, Thursday, Nov. 8, 2018. Judges on a federal appeals court heard arguments from Kamenar

WASHINGTON (AP) — A federal appeals court is weighing whether special counsel Robert Mueller's appointment to lead the Russia investigation was constitutional.

At issue Thursday is whether Deputy Attorney General Rod Rosenstein had the authority to appoint Mueller.

The special counsel's office says yes. But lawyers for a former aide to longtime Trump confidant Roger Stone say no. The aide, Andrew Miller, brought the case because he doesn't want to testify before a grand jury as part of Mueller's investigation into whether Donald Trump's Republican campaign coordinated with Russia in 2016.

Mueller is focusing on Stone's connection to WikiLeaks. American intelligence agencies have concluded that Russian agents were the source of damaging information on Democrat Hillary Clinton that WikiLeaks released during her 2016 presidential campaign against Trump.

Stone has denied any wrongdoing.