KipEsquire has an interesting post on plain language. His topic is teaching economics, but the lesson applies to legal instruction and writing too. He advocates the "pitcher and pie" principle:
[I]f I can't explain an economic, financial or legal concept to you over a pitcher of beer and a pizza pie, then I've failed as a teacher.
This principle applies to lawyers, because each lawyer, whether advising the client or advocating the client's cause, is a teacher.
(Thanks to Mike, who emailed me about this item.)