Former Peruvian spy chief, Vladimiro Montesinos, is seeking $20m (£10m) in damages for libel from Spanish judge Baltasar Garzon.
Ex-spy chief Vladimiro Montesinos is currently in jail for corruption
The lawsuit filed in Peru relates to allegations made in a recent book by Judge Garzon, which the ex-spy emphatically denies.
Montesinos, who announced the lawsuit in February, will testify on Friday.
He is currently serving 15 years in jail in Peru for corruption, and faces several other legal cases.
Judge Garzon had no immediate comment on the filing of the compensation bid.
Montesinos accuses Judge Garzon of libel for remarks in his book, A World Without Fear.
The Spanish judge maintains Montesinos made the comments during questioning in Peru in 2002.
Montesinos' lawyer Estela Valdivia said any compensation awarded in the case would be donated to charities working for peace and development in Peru and Ecuador.
Judge Garzon made the allegations in a book
The Peruvian judge in charge of the libel case has asked Mr Garzon to reply to questions ahead of a meeting between the two men.
Montesinos, a close aide of ex-President Alberto Fujimori, was found guilty of paying millions of dollars in bribes to TV executives to secure their support for Mr Fujimori's candidacy in 2000.
He was at the centre of the corruption scandal that brought down the government in 2000, when a video apparently showed him bribing opposition politician Luis Alberto Kouri.
Judge Garzon has made a name for himself taking on a number of high profile cases such as the attempt to extradite Chile's General Augusto Pinochet from London to Spain in the 1990s.