england-and-wales
At common law:
If a trespasser peaceably enters or is on land, the person who is in, or entitled to, possession may request him to leave, and if he refuses to leave may remove him from the land, using no more force than is reasonably necessary. However, if a trespasser enters with force and violence, the person in possession may remove him without a previous request to depart. An
owner of property is also entitled to take reasonable steps to prevent trespassers from entering his property. If the force or violence used in turning out a trespasser is excessive, the person who used such force himself commits a trespass upon the person of the person removed. To justify the expulsion of a trespasser, the person who uses force must be in
possession or acting under the authority of the person in possession.
1
As is typical, what is reasonable depends on the circumstances.
1 Quoted from Halsbury's Laws of England: 5th ed., vol. 97, para. 588; 4th ed., vol. 45, para. 1400. Cited cases:
Hemmings v. Stoke Poges Golf Club (1920) 1 KB 720. "Held, that the defendants were not liable, their right of entry being a defence to civil proceedings for the acts complained of [assault, battery and trespass]". Scrutton L.J.: "Shortly stated the question is whether, if an owner of landed property finds a trespasser on his premises, he may enter the premises and turn the trespasser out, using no more force than is necessary to expel him, without having to pay damages for the force used. So stated, common honesty and common sense would answer, 'Of course he may.'"
Thomas v Marsh and Nest (1863): stewards Marsh and Nest removed Thomas from a music festival at a county hall after he tried to enter without a ticket.
Jackson v Courtnenay (1857). "Held, further, that the possession of the vestry room was in the defendant as minister, so as to make the entry and remaining of the plaintiff, the clerk, therein after a prohibition by the defendant a wrong which justified the defendants in removing the plaintiff ..."
Shaw v Chairitie Esq (1850): a butler, Shaw, was removed from a house by the master of the house, Chairitie, after Shaw caused a disturbance.
Hall v Davis (1825): defendant Davis removed servant Hall from a house that was in Davis's possession.
Street on Torts, 14th ed. Page 313: "It is an established rule of common law that the person entitled to possession may use reasonably necessary force to remove a trespasser." Cites Hemmings.
Page 328: "Where it is necessary to do so, one may use reasonable force to defenced property in one's possession against any person threatening to commit or actually committing a trespass to it. But the defendant must have such possession of the property in question as would enable him to sue the claimant in trespass ... " Cites Holmes v Bagge and Fletcher (1853). Bagge and Fletcher lost - not because the power to remove a trespasser did not exist, but because they were not in possession of the property when they removed Holmes.
"To remain on land after the occupier's consent has been withdrawn is a trespass. ... Therefore, the defence of protecting property may be invoked by those who use reasonable force to eject such persons." Cites Green v Bartram (1830), Moriarty v Brooks (1834) and R v Burns (2010).
Green went to Bartram's house to demand repayment of a debt, Bartram said he could not pay, Green refused to leave until paid, Bartram sent for the police, removed Green from the house and locked him up in the outside toilet. The court held that if Green was causing a disturbance, Bartram would have been justified in removing him, but not justified in imprisoning him.
Moriarty accused publican Brooks of assault and battery after a dispute about payment for a drink. Brooks pleaded not guilty, claimed Moriarty was causing a disturbance and refused to leave when requested. The court found that the force Brooks used was excessive, having struck him under the eye and causing a wound.
Defendant Burns had driven with a prostitute to a secluded area. He then changed his mind about having sex with the prostitute and told her to get out of his car. She refused and so he dragged her out, causing some bruising and cuts. Essentially, Burns's defence was that "it is settled law that such force can be used to eject an individual from any property after he has refused to leave on request. By refusing, he becomes a trespasser and so can be removed." However, the court found that he was not acting in lawful defence of himself, another person or his property. "... the appellant could readily have regained exclusive possession to his vehicle by means not involving the use of force, that is, by simply driving the complainant back to the starting point."
Page 329: "The use of force will be unnecessary if the claimant would have ceased his interference with the defendant's property rights following a verbal request from the defendant." Cites Green v Goddard (1702): the court found that as the claimant (trespasser) had not yet used any force, the defendant (landowner) was not entitled to lay hands on him without first giving a verbal warning.
Page 329 continues: "However, a defendant is not required to make such a request when to do so would be obviously futile." Cites Tullay v Reed (1823) and Polkinhorn v Wright (1845). In Tullay, "Park J. -Laid it down as clear law, that if a person enters another's house with force and violence, the owner of the house may justify turning him out (using no more force than is necessary), without a previous request to depart; but if the person enters quietly, the other party cannot justify turning him out, without a previous request to depart."
