Prez 0bama can (unconstitutionally) pass legislation which Prez Trump subsequently does not have the power to override.
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Obma didn’t pass any legislation. He issued an Executive order. In this case an “Imperial Edict”, since Trump is unable to change it.
So Obama, think “Shadow Government,” gets away with not only pronouncing permanent Executive orders, and gets the SCOTUS to rule that Trump can’t cancel such.
Justice Thomas was correct - it should have been legislation. Obama skipped the process. It is still legislation - the province of the Congress. It is unconstitutional legislation since it was not passed by the Congress.