Some of the immutable laws of politics:

If it walks like a duck and it quacks like a duck, it's a duck.

If on the other hand it can't make a noise and waddles and then falls over, it's a lame duck.

And a president at the end of a second term with a highly partisan Congress ranged against him is as lame a duck as you will ever see.

So maybe it's time to rewrite those immutable rules. Because on Thursday the president looks anything but lame. The signature legislative achievement of the Obama years was to drive through the Affordable Care Act - or Obamacare as it is more widely known - that has given health insurance to millions more Americans.