Installing keylogging software on your employees' computers and using what you find to fire them is not OK, a German court has decided.

In a decision (in German) last week, the Federal Labor Court looked at the case of a web developer at a media agency who was fired for developing a computer game for a different company while at work.

The company discovered their employee's extra-curricular activities thanks to software it had installed on all of the staff's computers with a warning that all "internet traffic" would be logged.

The software did much more than that, however – it recorded every keyboard stroke and took screenshots at regular intervals and stored them on a company server.

Despite having worked at the company for four years, without issue, one month after the software was installed, the man in question's boss called him into his office and accused him of using the company computer for personal use.

I did it

The employee admitted he was working on a computer game – for his father's company – but argued that he only worked on it during his work breaks and that he had spent only three hours on the project over the course of four months.

Regardless, he was fired. And so he sued, arguing that the information used to fire him was gathered illegally. And the court agreed.

It decided that such a level of surveillance violated workers' personal rights and was an unlawful way of controlling employees. It did note, however, that such software could be used legally if it was to root out evidence of a criminal or serious offense.

Spending a few hours creating a computer game did not fit that description, the court decided, and even though he had admitted using the computer for private use – which was against the company's official guidelines – that was not sufficient cause to fire him and the company had acted disproportionately.

All of which is bad news for psycho bosses. It is, however, unlikely to impact one of the most recent high-profile cases of keylogging software on employees' computers – at the European Patent Office (EPO) in Munich – even though that installation was done secretly by a special investigation force set up by EPO president Benoît Battistelli.

Why? Because the EPO claims it is not beholden to any national laws, given its status as an international organization. ®