@BrikoX I see your point here.

And I see *their* point. If there are laws referencing antisemitism, the scope of those laws would be expanded w/o rewriting them.

So if employers are legally required to prevent racist speech in a workplace, and antisemitism is included in racism (which it should be), then if we talk politics at lunch and someone criticizes Israel, HR would be required to treat that as inappropriate speech for the workplace if they heard about it.

Assuming that the bill passed and was held up by courts.

Does this sort of thing actually happen? I mean, where a law redefines an English word (that's not specifically a legal term), affecting the scope of other laws?

Usually in practice "clarifying" laws are written more like "for purposes of X, Y means Z", not just directly "Y = Z", as though they owned the dictionary (and as though languages were defined by dictionaries).

Courts definitely have that power. The supreme court has declared that tomatoes are vegetables, for example.