 It is sufficient that any damage be merely temporary : in Cox v. Riley ( 1986 ) , the deletion of the program from a computer @-@ controlled machine , rendering it unusable , was held to constitute damage . This decision was followed in R v. Whiteley ( 1991 ) in relation to computer hacking , although that conduct is now dealt with under the Computer Misuse Act 1990 . In that case it was said that : 
