Professor Reinhard Merkel teaches Law and Philosophy of law in Hamburg.
He wrote an article in one of the best German newspapers ( F.A.Z.) in which he - meticuously- argues that the change of Crimea from Ukraine to Russia, is acceptable.
I translated the article with google, and have - so far- made a more understanable text of the first half of the article. The rest will follow soon, I hope.
Below you will see the whole article in german.