That's common in both European courts (look at e.g. the history of homosexual marriages in the EU) and in the US ("Citizens United").

The core issue is that no Constitution, in fact no law or decree at all can account for all possibilities that real life offers, and so all the bodies of law are up for interpretation all the time.

This is also the case in the UK. Where things are not crystal clear they are interpreted by judges and can become precedent (see the recent “definition of a woman” interpretation).

The issue highlighted by, say, the Owens vs Owens example, is that the law as it stood was clear and not open to interpretation, though obviously unfair. The law needed to be changed, which required parliament.