Slate's Explainer

Came across this while looking for the definition of the political phrase "stalking horse". Slate -- Microsoft's web magazine -- has a column called "The Explainer", which answers questions about the news. Interesting and, as far as I can tell, accurate. (Here's the Explainer's explanation of "stalking horse".) (Here's a better explanation from Wikipedia.)

An entry from four years ago answers the question, "Do delegates to the national political party conventions have free will?" In other words, are they allowed to deviate from the preferences expressed by the primaries or caucuses that chose them? The short answer is yes for Democrats, and for Republicans it depends on the state -- each state party sets its own rule in that regard. The Supreme Court struck down state laws controlling delegate allocation, according to this entry, which doesn't say why, but I imaging it's on freedom of association grounds.