TRESPASS TO THE PERSON
An assault is an act which intentionally causes another person to apprehend the infliction of immediate, unlawful, force on his person.
It was said in R v Meade and Belt (1823) 1 Lew CC 184, that 'no words or singing are equivalent to an assault'. However, the House of Lords have more recently stated that an assault can be committed by the Court of Appeal in R v Constanza  Crim LR 576.
It is much more authoritative that words will not constitute an assault if they are phrased in such a way that negatives any threat that the defendant is making. See:
Tuberville v Savage (1669) 86 ER 684
The claimant must have reasonably expected an immediate battery. Thus in Stephens v Myers (1830) 172 ER 735, the defendant made a violent gesture at the plaintiff by waiving a clenched fist, but was prevented from reaching him by the intervention of third parties. The defendant was liable for assault.
A battery is the actual intentional infliction of unlawful force on another person. It was stated in Cole v Turner (1704): 'The least touching of another in anger is a battery'. However, such a widely drawn principle must inevitably be subject to exceptions:
Collins v Wilcock  1 WLR 1172
Controversially, the Court of Appeal said that there must be a 'hostile touching':
Is 'hostility' a necessary element of battery? In Re F  2 AC 1 (at p 73), Lord Goff said that he doubted whether it is correct to say that the touching must be hostile, and further: 'the suggested qualification is difficult to reconcile with the principle that any touching of another's body is, in the absence of lawful excuse, capable of amounting to a battery and a trespass.'
If a person intentionally applies force directly to another, the claimant has a cause of action in trespass. However, if a person does not inflict injury intentionally, but only unintentionally, the claimant only has a claim in negligence.
The defendant's act must cause direct damage, but see:
Scott v Shepherd (1773) 2 B1 R892
False imprisonment is the unlawful imposition of constraint upon another's freedom of movement from a particular place.
This tort protects a person from restraint and does not give a person absolute freedom of movement. Thus, if there is a reasonable escape route there will be no false imprisonment. See:
Bird v Jones (1845) 7 QB 742
Robinson v Balmain New Ferry  AC 295
Can a person be falsely imprisoned without his knowledge? Yes, according to the Court of Appeal and the House of Lords in, respectively:
Meering v Graham-White Aviation Co Ltd (1920) 122 LT 44
However, Lord Griffiths did state in the latter case: 'If a person is unaware that he has been falsely imprisoned and has suffered no harm, he can normally expect to recover no more than nominal damages ...'.
Can an omission to release a person constitute false imprisonment? Not according to the House of Lords, at least where a person has consented to some degree of constraint on their movement. See:
Heard v Weardale Steel, Coal & Coke Co  AC 67
THE RULE IN WILKINSON v DOWNTON
The rule in Wilkinson v Downton relates to the intentional infliction of harm. This is not actually a trespass to the person but a separate analogous tort. See:
Wilkinson v Downton  2 QB 57
The Court of Appeal upheld this rule in Janvier v Sweeney  2 KB 316.
Consent may be given expressly by words or be implied from conduct.
A person is deemed to consent to a reasonable degree of physical contact as a result of social interaction (see Collins v Wilcock, above).
Those who take part in sports also consent to a reasonable degree of physical contact during the course of play, ie within the rules, even to the risk of being unintentionally injured. However, there can be no consent to deliberate acts of violence (R v Billinghurst  Crim LR 553).
What is meant by 'informed consent' and does English law recognise such a doctrine? Informed consent is the notion that consent is not valid unless all the risks of a surgical procedure have been explained. A person may not bring an action, in trespass or negligence, on the ground that they had not been informed of the potential consequences.
The issue in trespass is whether the patient consented to what was being done, and the issue in negligence is whether the patient should have been informed of the risks.
Every adult has the right to refuse medical treatment even if it will result in permanent injury or even death. However, a person may de deprived of his capacity to decide either by long term mental incapacity or temporary factors such as unconsciousness or confusion or the effects of fatigue, shock, pain or drugs. In such a case, it is the duty of the doctors to treat him in whatever way they consider, in the exercise of their clinical judgment, to be in his best interests.
The powers of arrest, exercisable by a constable or a private citizen, are contained in the Police and Criminal Evidence Act 1984. An arrested person must be told, as soon as is practicable, that he is under arrest; and the grounds for the arrest (s28). Private citizens making an arrest must, as soon as is reasonable, hand the arrested person over to the police. Only reasonable force may be used to effect an arrest.
The police must not act unlawfully. See:
Collins v Wilcock  1 WLR 1172
It has long been an established rule of the common law that a person may use reasonable force to defend himself, another person, or his property from attack. What is reasonable force is a question of fact in each case.
A person may make a mistake as to their right to self defence. In such a situation, the criminal law allows a defendant to be judged on the facts as he honestly believed them to be: R v Williams (Gladstone) (1984) Cr App R 276 and Beckford v R  AC 130.
In Re F (above), a case concerning when medical treatment can be justified when given without consent, Lord Goff having explained public necessity and private necessity stated:
"There is, however, a third group of cases, which is also properly described as founded upon the principle of necessity and which is more pertinent to the resolution of the problem in the present case. These cases are concerned with action taken as a matter of necessity to assist another person without his consent. To give a simple example, a man who seizes another and forcibly drags him from the path of an oncoming vehicle, thereby saving him from injury or even death, commits no wrong. But there are many emanations of this principle, to be found scattered through the books".
Lord Goff went on to say that the present case was concerned with action taken to preserve the life, health or well-being of another who is unable to consent to it. The basic requirements, applicable in these cases of necessity, were "not only (1) must there be a necessity to act when it is not practicable to communicate with the assisted person, but also (2) the action taken must be such as a reasonable person would in all circumstances take, acting in the best interests of the assisted person".