So, reading a bit, it seems to work like this.

There is a jury duty in the sense that if you are asked to serve as lay judge you can not refuse. However, in practice the system is set up so that only volunteers get asked.

Every 4 years, each municipal council (kommune) provides a list (grundlisten) of candidates for lay judges (nævning). The list must be representative of general demographics. To be eligible for the list, you must be "suitable" for the role (which seems to mean you should not have a criminal background), and you must not be a lawyer, prosecutor, judge, or police officer. The cities can use their own procedures to compile the list, but in practice the way it works is you write to the selection committee giving your name, age, job title, and motivation for why you want to be a lay judge.

The lists are combined, and about 10,000 people are randomly selected from them. If you are selected you have a duty to serve. You serve for a period of 4 years, and will typically sit on 4 to 5 cases per year.

https://www.frederiksberg.dk/politik/kommunalbestyrelsen-og-... http://www.domstol.dk/saadangoerdu/tildigderer/naeavningdoms...

Thank you for this comment, that's more than I could find about it, even with Google translate it can be quite hard to understand what is written on a page in a language you do not understand.

Wow if you are called to serve that'd make you quite unattractive to employers, and would limit your movements e.g. working abroad?