The Opposites in Jurisprudence

DON't do unto others what you would not like done to yourself.

OR

DO as you would be done by.

Two sides of the same coin.

Lord Mackay of Clashfern in the Moorcock Test

It is not about what you "should have done", it is about what you "did" or "did not" do.

Is this the difference between Scottish and English & Welsh law?

Discuss.