Battery is a summary offence. Assault and battery have no statutory definition. The definition and all elements of the offence of battery are set out in case law. The punishment (maximum 6 months imprisonment) is set out in statute under s.39 Criminal Justice Act 1988.
On the issue of consent specifically related to battery, see Goff LJ's comments in the following case:
Collins v Wilcock [1984] 3 All ER 374 Case summary
See also:
Donnelly v Jackman [1970] 1 All E.R. 987 Case summary
Physical force
Physical force is perhaps a misleading phrase in that it suggests a high level of force however, any touching will suffice:
Faulkner v Talbot [1981] 3 All ER 468
Lord Lane CJ defined unlawful physical force as
"any intentional [or reckless] touching of another person without the consent of that person and without lawful excuse. It need not necessarily be hostile, rude, or aggressive.”
Mens rea of battery
Intention to apply unlawful physical force or,
Being reckless as to whether such force is applied (Subjective reckless applies R vParmenter [1991] 94 Cr App R 193 Case summary)
