Case law on the abuse of process has been set out by an inspector in a recent remitted appeal concerning the use of a building in the back garden of a house in south-east London (DCS Number 200-010-524) .
In this case the council claimed that the appellants were too late to directly challenge the findings of the previous inspector by seeking a further opportunity to argue whether the building in their garden was in ancillary use or was a self-contained unit of accommodation.
In brief, the current inspector noted that the previous inspector had been considering, first and foremost, whether planning permission should be granted; he was not required to make a fact and degree judgement on the lawfulness or otherwise of the outbuilding. She was not satisfied, therefore, that the whole matter was fairly and squarely before the previous inspector. Accordingly, she found that the appellants were not prevented from advancing arguments in respect of the use and effect of the outbuilding by way of abuse of process.
Here is the case law as set out by the inspector:-
The rule in Henderson v Henderson  established the principle that a party is expected, indeed required, to present their entire case during the course of legal proceedings. The act of raising a line of argument in subsequent proceedings which could and should have been raised in the earlier proceedings, but was omitted from negligence, inadvertence or accident constitutes an abuse of process and leaves the subsequent proceedings vulnerable to a strike-out application. In Thrasyvoulou v SSE , the House of Lords confirmed that the principle applied to planning decisions. A distinction could be drawn between a decision to grant or refuse planning permission and a decision on the legal status of the alleged development.
The rule was further explained in Barrow v Bankside Members Agency Ltd , and expanded upon in Divine-Bortey v Brent LBC . When a matter becomes the subject of litigation between them in a court of competent jurisdiction, parties are required to bring their whole case before the courts so all aspects of it may be finally decided. In the absence of special circumstances, the parties cannot return to the court to advance arguments, claims or defences which they could have put forward for decision on the first occasion, but failed to raise. The rationale being the desirability, in the general interest as well as that of the parties themselves, that litigation should not drag on for ever. This is an abuse of process at which the rule is directed.
The subject of court challenges is covered at section 5.4 of DCP Online.