I could be wrong on this...
But I believe that drug use/abuse i written into the code of conduct with a guaranteed suspension of 4 games for a first offense 8 or 10 games for a 2nd offense and a season for a 3rd. This includes PEDs, Marijuana, Cocaine and other such drugs. This was written up a long time ago, aka well before Goodell took the reigns.
As for other legal issues, they are at the commissioners discretion as to what happens. When in doubt, players suspensions (Especially stars like Ray Rice) are not going to be that long in an attempt to keep them on the field and keep making money for the league. There are numerous examples across the league annually, and historically (as in way before Goodell)
Blame the commish for plenty of things, but this is a stupid reason to hate on him.