Case law, also known as common law, is a British legal tradition. Most of the EU does not follow the common law tradition. There may be supreme courts, but the notion of binding precedent, or stare decisis as in the US legal system does not exist. Appeal and Supreme court decisions may be referenced in future cases, but don't establish precedent.

<https://en.wikipedia.org/wiki/Precedent>

The equivalent doctrine under a civil legal system (most of mainland Europe) is jurisprudence constante, in which "if a court has adjudicated a consistent line of cases that arrive at the same holdings using sound reasoning, then the previous decisions are highly persuasive but not controlling on issues of law" (from above Wikipedia link). See:

<https://en.wikipedia.org/wiki/Jurisprudence_constante>

Interestingly, neither the principle of Judicial Review (in which laws may be voided by US courts) or stare decisis are grounded in either the US Constitution or specific legislation. The first emerged from Marbury v. Madison (1803), heard by the US Supreme Court (<https://en.wikipedia.org/wiki/Marbury_v._Madison>), and the second is simply grounded in legal tradition, though dating to the British legal system. Both could be voided, possibly through legislation, definitely by Constitutional amendment. Or through further legal decisions by the courts themselves.

No, case law is when the interpretation of the law is ambiguous in specific cases where the law as written intends for a specific meaning.

This is different, it is intentionally ambiguous precisely so bureaucrats get to choose winners and losers instead of consumers.