Legitimate lawsuit or political posturing?

The big news last week was the lawsuit filed by California and 15 other states challenging President Trump’s declaration of an emergency related to border security and the building of a physical barrier on the southern border. The reaction was a great deal of political hyperventilating from both sides of the political spectrum.
So, after everyone has taken a breath, what should rational taxpayers think about this lawsuit and the dozens of other lawsuits filed by California against the Trum