There isn't. Until very recently (Human Rights Act) justice was deemed to have been served by bringing all evidence to the court.

The ECHR gave some rights which now have to be balanced against justice but its still anything goes. There is some interesting court ruling on Azima Rakia hacking case too.

Interestingly the courts are waiting for the case where computer hacking infringes on people's right to privacy...

Rather than pretend i'll quote a leading case. Woman faked her hand palsy and was filmed illegally by the insurance agents...this is the appeal rulign (so important in uk legal terms)

Jones v University of Warwick [2003] EWCA Civ 15
https://www.bailii.org/ew/cases/EWCA/Civ/2003/151.html

That leaves the issue as to how the court should exercise its discretion in the difficult situation confronting the district judge and Judge Harris. The court must try to give effect to what are here the two conflicting public interests. The weight to be attached to each will vary according to the circumstances. The significance of the evidence will differ as will the gravity of the breach of Article 8, according to the facts of the particular case. The decision will depend on all the circumstances. Here, the court cannot ignore the reality of the situation. This is not a case where the conduct of the defendant's insurers is so outrageous that the defence should be struck out. The case, therefore, has to be tried. It would be artificial and undesirable for the actual evidence, which is relevant and admissible, not to be placed before the judge who has the task of trying the case. We accept Mr Owen's submission that to exclude the use of the evidence would create a wholly undesirable situation. Fresh medical experts would have to be instructed on both sides. Evidence which is relevant would have to be concealed from them, perhaps resulting in a misdiagnosis; and it would not be possible to cross-examine the claimant appropriately. For these reasons we do not consider it would be right to interfere with the Judge's decision not to exclude the evidence.

Mr Weir's submission that we should determine the issue on the basis of the facts as they were before the district judge is not realistic. Nonetheless, it is right that we should make clear that we do not accept that the criticism of the claimant's legal advisers for deciding not to reveal the contents of the video films in issue to their medical experts is justified. It was sensible to defer doing so until it was known whether the evidence could be used. While not excluding the evidence it is appropriate to make clear that the conduct of the insurers was improper and not justified. We disagree with the indication by Judge Harris to the contrary. The fact that the insurers may have been motivated by a desire to achieve what they considered would be a just result does not justify either the commission of trespass or the contravention of the claimant's privacy which took place. We come to this conclusion irrespective of whether Mr Weir is right in contending that in this particular case the evidence could be obtained by other means.

Excluding the evidence is not, moreover, the only weapon in the court's armoury. The court has other steps it can take to discourage conduct of the type of which complaint is made. In particular it can reflect its disapproval in the orders for costs which it makes. In this appeal, we therefore propose, because the conduct of the insurers gave rise to the litigation over admissibility of the evidence which has followed upon their conduct, to order the defendants to pay the costs of these proceedings to resolve this issue before the district judge, Judge Harris and this court even though we otherwise dismiss the appeal. This is subject to Mr Owen having an opportunity to persuade us to do otherwise. In addition, we would indicate to the trial judge that when he comes to deal with the question of costs he should take into account the defendant's conduct which is the subject of this appeal when deciding the appropriate order for costs. He may consider the costs of the inquiry agent should not be recovered. If he concludes, as the complainant now contends, that there is an innocent explanation for what is shown as to the claimant's control of her movements then this is a matter which should be reflected in costs, perhaps by ordering the defendants to pay the costs throughout on an indemnity basis. In giving effect to the overriding objective, and taking into account the wider interests of the administration of justice, the court must while doing justice between the parties, also deter improper conduct of a party while conducting litigation. We do not pretend that this is a perfect reconciliation of the conflicting public interests. It is not; but at least the solution does not ignore the insurer's conduct.