The law, as it is practiced, is much more important then the law, as it is written.
That's not a accurate at all; language of law always requires interpretation and application to the facts, that doesn't change in a civil law system. Moreover, the different role of the judiciary isn't germane to what GP referenced, which was different approach to executive enforcement practices and priorities.
Even if the law is not under discretionary interpretation[1], prosecution, analysis of evidence, verdicts of guilt or innocence, policing methods, and everything else is. Counter-revolutionary activity was hardly the only thing people were purged for - espionage and treason were other incredibly popular charges. If Stalin's officials were to be believed, half the country earned its daily bread by selling the secrets of the motherland to nebulous foreign powers.[2]
Not to say that the USSR was a shining paragon of legalism in 1987, but the letter of the law was not what made it different from 1937. The USSR had all sorts of, uh, wonderful laws, most of which were enforced with incredible discretion.
[1] Although, given the incredibly broad and poorly defined nature of Article 58, its application was 100% based on discretionary interpretation. http://www.cyberussr.com/rus/uk58-e.html#58-1a
[2] Or at least, that's how Solzhenitsyn tells it.
a) bringing a civil law system to argue a point about a common law. It's like arguing about Linux with BeOS examples.
b) saying that the law was more or less the same while it has changed rather dramatically. Saying the US law has not significantly changed between Coolidge and Reagan would be less false than this.