Source? Because this seems like a whole lot of nonsense considering NOBODY EVER USES "STATE OF LAW". You think the EU is potatoes too?

The concept of a state of law does not deal with the content of laws...

Tell me, is there rule of law when you have no access to a judge? How can you pretend to have rule of law when 'due process' is gone? Where is rule of law when the principle of equality is forgotten and the law no longer applies to certain citizens? Rule of law and fundamental rights go hand in hand. You cannot have a rechtsstaat in which these fundamental principles are not present. Only a fool would think otherwise.

just a part of the "state of law" concept

Did you just make this shit up?

"rechtsstaat" is in fact an English word borrowed from the German language where the whole concept came from in the first place...

Holy cow, you're kidding me. Ja, 't is een leenwoord. Iedereen gebruikt het. Niemand vertaalt het als 'state of law'. Ze vertalen het naar 'rule of law'. Good job on reading an intro to law. Next time don't skim, potato.