Article by Holden N. Slutsky
The Harman undertaking, stemming from Home Office v Harman  1 AC 280, is an undertaking to Court implied by law not to use documents disclosed by one party to the other in any proceedings for an ulterior or collateral purpose.
Moreover, an implied undertaking (known as the Taylor’s implied undertaking) extends the principle to documents obtained under criminal investigations and actions (Taylor and Anor. v Director of the Serious Fraud Office  2 A.C. 177).
However, a release from such implied undertakings, in some circumstances, may be granted by the Court.
In Wong Lee Yuk Ping Agnes ("Wong") v The Commissioner of Police & Wah Sun Hong Limited ("Wah Sun Hong") HCMP 722/2019, Wah Sun Hong had made discovery in civil proceedings against Wong in respect of a claim, while also supplying documents to the police in support of a criminal complaint on the same matter, alleging they were relevant to the civil action. These documents were subsequently supplied by the police to Wong in order for her to respond to the accusations.
However, a number of crucial documents disclosed to the police had not been discovered in the civil action.
Wong, represented by Jeevan Hingorani leading Lawrence Cheung, sought release from her implied undertaking to Court that she would not use the police-supplied documents for any collateral purpose, in particular the civil action.
Wah Sun Hong had argued in numerous correspondence and at the hearing that no implied undertaking existed; the application was an abuse of process and Wong should simply have applied for specific discovery.
These arguments were rejected by the Court of First Instance which ordered release so that Wong could identify with precision (without breach of the undertaking) the documents of which she could proceed to specific discovery.
(Comment: It was accepted by Wah Sun Hong, in court, that an implied undertaking did exist in respect of the subject documents. Wah Sun Hong did not challenge the law as to restraint of use for a collateral or ulterior purpose. Further, it was not argued by Wah Sun Hong that use of the documents by Wong in a civil action would not constitute a collateral purpose. It would follow then that the application for release could not have been an abuse of process.)