It did not work. I did insurance litigation for 15 years, and we shuddered when we saw one of those "plain language policies" coming. You think it's 'the common tongue', but nobody knows what it means from a binding, legal point of view.
Same thing with construction contracts. The AIA Standard Form is the way to go because every word has been litigated and has a single meaning. Many words in everyday language have multiple meanings, and most ordinary conversations assume a great deal that isn't said. That leads to problems when binding legal meaning is placed on ordinary conversational English. Those contracts drawn up on notebook paper on the tailgate of a pickup truck are just fine until the parties have a disagreement and nobody can agree exactly what they meant by "rain day".
I thought our residential contractor was going to bust a gut laughing when we handed him a standard AIA form. But later, when he tried to weasel out of the completion date, "rain day" was precisely defined and the allowance for completion was specified.
That's not necessarily a case of using jargon ~ it's called adjusting for risk ~ probably more like trying to describe an actuarial table in the course of defining "policyholder". When it comes to the type of federal regulation that might well be read by 250 million Americans, it has to be in a language they can understand, and that their lawyers can understand too.
Not to say I'm smarter than a bunch of lawyers, but, yes, it's true, some people are just naturally so.
At any one time there are no more than a couple of dozen people in Washington with the ability to write legislation and regulations correctly. They are kept busy at that until they're worn out. Eventually Congress will have to hire a couple to deal with the problem.