The chief executive of billion-dollar start-up Dovetail has conceded his relationship with an employee was an error of judgment and plans to use hundreds of text messages between them to prove it was consensual.

Dovetail lawyer Bethany Lo Russo alleges the company’s co-founder Benjamin Humphrey forced her into a non-consensual relationship while his company turned a blind eye. She is suing Dovetail and Mr Humphrey for sexual harassment and discrimination in the Federal Court, filing documents that paint the firm’s workplace as one heavy with drinking.