BUENOS AIRES—An Argentine federal appeals court decision Friday opened the door for Vice President Amado Boudou to be called to testify as a suspect in a criminal investigation.

On Friday, a three-judge panel rejected a request by Mr. Boudou's attorney to have the vice president removed from the case on grounds that there was no criminal wrongdoing. The ruling paves the way for federal judge Ariel Lijo to call the vice president to testify in the coming weeks, according to people familiar with the case. Judge Lijo would then...