Gordon Smith posts a round-up of Law Professor Teaching Loads. It seems that UM's load – 10 credits / year – is no longer as outstanding as it seemed when I was on the market more than a decade ago. Other schools have caught up. So, we still look OK compared to our competitors, but more from the viewpoint of being part of the pack rather than leading it.
As Prof. Smith himself notes, his survey doesn't take into account the complicated question of sabbaticals. If your school were to give you one term off in seven, then the ten credit load would really only be about 8.6 credits/term — a huge difference.
I suspect that policies on sabbaticals vary even more than teaching loads. I've heard of schools where you get one in seven as of right, I've heard of schools where you never get them unless you find outside money to buy your time (which is very hard to find in the law teaching biz, unlike the social sciences and the humanities … not to mention the sciences where it seems commonplace). And then there's the schools where Deans dole out time off as rewards to friends, to productive scholars, to people trying to finish books, or as political chits to buy faculty cooperation on divisive issues.
Then, there's our policy: all junior faculty get one term off of 'writing leave' some time before tenure. But senior faculty have to buy their time off by teaching extra. “Bank” five credits and you are eligible to ask for a term's leave, bank ten and you can ask for a year, but you don't necessarily get it right away depending on teaching needs.
Having duly 'banked,' I will be on leave this coming Spring.