And by bringing up that people were charged for doing EXACTLY the same thing in the 50’s they admit that this is EXACTLY how the law works.
When you are losing your case based on the factual information provided, argue the law.
When you are losing your case based on the law, argue the facts of the matter.
If both the law and the facts are against you, hammer your fist on the table and accuse your opponents of the very worst motives you can imagine.
And if Joe McCarthy had the worst motives you can imagine, then you are on very thin ice indeed.