Cicil law courts are bound to apply the law and certainly don't have the right to rewrite the law in most cases (the german constitutional court for example has the power to undo laws), but they still need to interpret the words of the law and the meaning of those words changes over time. For example the anti discrimination laws would as long as maybe 30 years ago never have encompassed discrimination for LGBTQ* people. The laws have not changes substantially, but the interpretation of those words has definitely changed and as such, rulings that were not possible then are standard now. Very often, rulings do have a law-like quality - even if strictly speaking, they are not laws. From the top of my head I can cite one example from the road laws in germany: There's a thing called "Bicylcle roads" and the legal scripture (Straßenverkehrsordnung) says that cars are required to maintain a "suitable speed." A single influential court decision pegged that to 30km/h about a decade or so ago - which has finally been fed back into the legal text this year.
So while strictly speaking, no court was bound to that decision, the decision was still referenced by many other court cases and became some sort of de-facto law.
Just a nitpick, but the constitutional court doesn't have the power to rewrite the law either. The only thing it can do is declare a certain law unconstitutional (because legally, the constitution always trumps individual laws) and then the ball is back in the court of the legislative branch which may repeal or amend the law.
The constitutional court can declare laws Or parts of laws as not applicable and can require laws to be made and in specific cases it’s decisions are equivalent to a law (mostly regarding disputes which law applies, state vs. federal law, where certain responsibilities lie and in cases where the constitutional court decides that a law violates the constitution and is immediately declared void.) §31 BVerGG would be the applicable paragraph. There a nice summary in English on the courts own page https://www.bundesverfassungsgericht.de/EN/Verfahren/Wichtig...
At least in my country the law that is ruled unconstitional loses it's power immediately, unless the constitutonal court itself grants some grace period. The thing is: constitutional court can't by itself decide which laws to start analysing next, there must be some formal complaint by either the President, group of members of parliament, or several other institutions, including IIRC any complaint signed by at least 100k citizens.
So while strictly speaking, no court was bound to that decision, the decision was still referenced by many other court cases and became some sort of de-facto law.