In an unusual act of contrition, a state court judge has publicly apologized and agreed to pay $100,000 to Silicon Valley billionaire Tom Siebel for besmirching him in a lawsuit she filed as an attorney more than a decade ago.

"I write to express my sincere regret for pursuing claims against you that were determined to be without merit," San Mateo Superior Court Judge Carol Mittlesteadt wrote in an apology to Siebel that was released Thursday.

Mittlesteadt, who was appointed to the bench in 1998, also acknowledged her actions "may have caused substantial expense and inconvenience, and damage to (Siebel's) reputation and good name."

The apology was part of a settlement that ends a 12-year legal odyssey that began after business software maker Siebel Systems Inc. fired its top sales representative, Debra Christoffers.

Representing Christoffers, Mittlesteadt filed a wrongful termination and sex discrimination lawsuit against Siebel as well as the company. A court ruled the charges against Siebel were unfounded.

Siebel, who is worth an estimated $1.9 billion, hopes the judge's public penitence teaches lawyers not to fabricate claims against wealthy individuals or large companies in hopes of extracting a large settlement.

He said in an interview that he's surprised Mittlesteadt is a judge.