AceShowbiz - James Franco has asked the judge overseeing Johnny Depp's bitter defamation case against his ex-wife to keep his testimony under lock and key.

The actor has been subpoenaed for a deposition in regards to the legal spat, but he wants his involvement kept private.

According to a legal letter, obtained by The Blast, Franco's attorney is demanding his client is given a guarantee that whatever he says in a deposition is sealed.

And he insists there should be financial implications if Depp or anyone leaks the transcripts.

"I am checking with Mr. Franco regarding his availability during the weeks of January 20 or February 10," the letter reads. "Please let me know if any dates during those weeks do not work for you. Please also provide me with an estimate regarding the time that each side will need to question him."

"Prior to agreeing to appear, we request that a Protective Order re Confidentiality be entered by the Court that contains, among other provisions, the following: the transcript will not be used for any purpose other than the litigation; if any portion of the transcript is submitted to the Court, it be submitted under seal; no party can discuss the fact that Mr. Franco's deposition is being or has been taken with any third party or anyone else including the press; no party can discuss Mr. Franco's testimony and/or the transcript with (or show any portion of the transcript to) a third party or anyone else including the press; and if any party violates the confidentiality provisions, that party is responsible for liquidated damages (in an amount we can discuss)."

Franco was spotted with Depp's ex, Amber Heard, inside the couple's apartment building elevator just 24 hours after the fight which rocked their marriage and led to a bitter divorce battle and allegations of abuse from both parties.

Depp is suing his ex-wife for defamation after she suggested she was a victim of domestic abuse in a newspaper op-ed piece.