'Gagging clauses' - NDAs or non-disclosure agreements - have been rarely out of the headlines in recent months. High profile cases in business, politics and celebrity life have prompted calls for an outright ban, particularly when used to cover up apparent sexual impropriety. This programme explores the rise and rise of the NDA. Who uses them, why, and when? Are they an invisibility cloak, helping the rich and powerful to silence victims of their bad behaviour? Or are they a vital tool for those looking to protect personal privacy and business interests? Tiffany Jenkins investigates.

Producer: Dave Howard