"The general rule – IP ownership

The general position under English law is that IP rights created by an employee within the course of employment automatically belong to the employer; where there is any doubt as to whether an employee or their employer owns IP rights, the relevant legislation largely favours employers."

It's been that way for decades, while the UK was in EU.

I had to get it written into an employment contract that Open Source activity outside of work was my own.

I mean, fair enough if the contract mentions working in your free time to use / contribute to the IP of the company you work for (or that of the competitor), but I was more referring to working on hobby projects not relating to your work.

The situation isn't any different in NL either. Although there is no blanket your-company-owns-your-**s policy (your IPs), the general rule is: if you create something in your spare time that your employer could well have paid you for (i.e. it's in line with your job description), the IP belongs to your employer.

The idea behind this is that your employer pays not just for your time, but also for the skills you acquire during your work. Therefore, the output of those skills has at least partial ownership. There's a huge gray area which contains liabilities and opportunities for both sides, which is why most companies insist on signing off on personal projects. The alternative is fighting it out in front of a judge, should it ever come to that.

It certainly was a thing working for Telefónica in Germany. We needed to get separate permission to be allowed to do work/volunteering outside of the main role, which was conditional on you being able to complete the main task.

I heard a story of someone who had this permission revoked because they worked weekends as a DJ in Berlin, and would often take sick days/turn up late on Mondays to deal with the hangover.

Yes, this is normal in Germany. The idea is that you're legally only allowed to work 40-ish hours per week and your employer is legally required to ensure that you observe break times and at least 24 hours of rest on the weekend. In turn you are usually required to get signoff if you want to do another job on the side, though I think volunteer work is generally allowed. I have no idea how this works for part-time jobs and why your employer can allow you to take a second job if doing so will violate the legally mandated recovery periods.

I definitely was required to get written approval in multiple companies I worked at in Germany.

Also it is legally enforceable as in it can be considered a valid and completely legal exception to usual termination protection.

It should be legal. I dont see the problem with having terms like this. There are plenty of other companies to choose from if you are a developer. From a company perspective it makes 100% sense to have terms that restricts when a developer is allowed to work on a project.

It should not be legal. You exchange your time to produce money for the company, and that's it. You should be able to do whatever you want out of the company hours, and I don't see how that can be a problem. It makes 100% sense from a worker perspective to not have your company have complete control of you. There are plenty of other workers to choose from if you are a company, in case you are dissatisfied with an employee.

> It should be legal.

It should be if consideration is provided.

I do think there's an argument to be made whether the base salary counts as consideration for things outside of the defined working hours though.