Offence 1: Unauthorised Access

Offence 1 of the Computer Misuse Act 1990 is unauthorised access to computer material. This means knowingly opening, viewing or using programs or data on a computer when you do not have the owner's permission. The key word is unauthorised: the access happens without permission. Permission must cover the particular files or programs you open.

The offence is complete at the moment of access. Nothing has to be changed, damaged, copied or stolen. Suppose a pupil at a youth club knows that the committee's trip budget is private, but opens the folder on the club laptop and reads the figures. They then close the folder without editing anything. They have still committed Offence 1, because they accessed data they were not allowed to see. The same is true of opening someone else's program just to look at how it works.

This is why it is wrong to think that hacking, meaning accessing a computer without permission, is only illegal if data is stolen or damaged. The question is whether the access was authorised, not whether harm was caused. Offence 1 is the basic offence; Offence 2 and Offence 3 involve additional intentions or effects.