Dishonest assistance, or knowing assistance, is a type of third party liability under English trust law. It is usually seen as one of two liabilities established in Barnes v Addy,[1] the other one being knowing receipt. To be liable for dishonest assistance, there must be a breach of trust or fiduciary duty by someone other than the defendant, the defendant must have helped that person in the breach, and the defendant must have a dishonest state of mind. The liability itself is well established, but the mental element of dishonesty is subject to considerable controversy which sprang from the House of Lords case Twinsectra Ltd v Yardley.[2]