force49. Any conduct exceeding ordinary acceptable boundaries will suffice; it is unnecessary for there to be an element of hostile intent50.
25.If a person consents to the infliction of physical contact a claim for trespass to the person will not lie. The claimant must prove an absence of consent as part of establishing his claim51. There is an initial presumption that the claimant consents to such contact as is “generally acceptable in everyday life”52. Consent, to be effective, should be freely given:
“a man cannot be said to be truly ‘willing' unless he is in a position to choose freely, and freedom of choice predicates, not only full knowledge of the circumstances on which the exercise of choice is conditional, so that he may be able to choose wisely, but the absence of any feeling of constraint so that nothing shall interfere with the freedom of his will” 53.
However, whilst it is clear that an abuse of authority may negate apparent consent54, the mere fact that consent was obtained by an assertion of authority is insufficient. In Wainwright v Home Office55 the Court of Appeal held that consent to strip searching an inmate’s visitors, obtained by prison officers indicating that the visit would not go ahead unless the searches were undertaken, was not vitiated by duress. The decision also illustrates another important principle, namely that consent can only be raised against the claimant where he consented to the nature and the degree of force that was actually used. In Wainwright the defendants could not rely upon the claimants’ consent because the searches had been conducted in breach of procedures, whereas the consent had been to searches carried out in the prescribed manner (although the majority of the claim failed for other reasons, as discussed below).
49 For example see Wilson v Commissioner of Police for the Metropolis  EWCA Civ 434 where the claimant sustained serious head injuries, for which the defendant was liable, as a result of a police officer deliberately barging him to the ground.
50 Wainwright v Home Office  4 All ER 969 at para. 9 approving Collins v Wilcock (above) on this point.
51 Freeman v Home Office (No. 2)  QB 524.
52 Collins v Wilcock (above) at 1177.
53 Bowater v Rowley Regis Corp  KB 476 at 479.
54 See Freeman v Home Office (no. 2) (above).
55  3 All ER 943 CA; the case went to the House of Lords on other grounds (see para. 32 below).