Says Bryan Garner, trying to figure out why lawyers write so badly.
The poor lawyers! They are trying to sound like the lawyers who were trying to sound like lawyers who were trying to sound like lawyers who were... etc.
The stakes are high and the desire to sound professional and learned overcomes a native speaker's capacity for natural speech.
But there's also the problem that the arguments judges and lawyers are putting together are full of gaps. Clear speech would make that obvious.