As a trainee, language can be just as much your foe as your fiere. Some of it (the notwithstandings and hithertoes and hereinbefores) are just sprinkled in there to confuse people, but there's also a legitimate Fachsprache that a trainee needs to get to grips with if he wants to be any good at convincing people he has the first clue about what he's up to.
If you go up to court to watch what happens there (and anyone is entitled to do that, so you should feel free to), you'll encounter all manner of peculiarity of language. Try to get all the episodes of Boston Legal out of your head, though; the judge is not called, "Your Honour", and at no point will a sudden dramatic reference be made to "Exhibit A". (The judge is always, "My Lord/Lady" or "Your Lord/Ladyship", and pieces of evidence are "productions".) It might seem strange too hearing a lawyer telling the judge that the person on the other side is their "friend". Why is the judge meant to care that the other lawyer is your pal? What if you're not friends any more? Or what if it's your ex on the other side, or your mum? In fact, that's just the word used to mean "the other guy". You'll also hear solicitors referred to more often as "agents" and advocates as "counsel". The reason for that is historic, which coincidentally is also the reason for pretty much every strange thing about the courts and law and lawyers.
As well as using words you might not be expecting, we like to keep folk on their toes by saying words in strange ways. Reading the word, 'decree', you'll probably pronounce it, 'decree', just like every other person in the English-speaking world; but do that in court and expect a hushed snigger from the other agents behind you. It's pronounced, 'decree', because… well I don't know why, but you should just accept it. The same goes for the record. The good thing is that once you've said those words like that often enough it'll feel weird to say them any other way. In fact the only reason you won't find yourself saying that One Direction have been dropped by their record label is that obviously that would just never happen.
Eventually, we run out of ways to make the English language difficult for people; but that's not a problem, because then we just move on to Latin. Phrases like inter alia, et separatim and a coelo usque ad centrum roll easily off the competent lawyer's tongue. But that can be tricky for trainees, particularly those who have been through our modern comprehensive school system. I'm not saying it's a travesty that state schools don't teach Latin any more, but I'd gladly swap all the time I spent being driven with a cattle prod through Joseph Conrad's Heart of Darkness (which despite being a novella is literally the longest book in the history of the world) for not feeling like a total eejit the first time someone said a mensa et thoro to me.
Which brings me in what I don't mind saying is a perfectly seamless link onto my next topic: what happens when someone whips one of these phrases out at you and you have no idea what it means? I saw that happen recently in the Family court, when the sheriff asked the agent if she was asking for the other side's motion to be denied in hoc statu. There was a pause, and the poor soul said, "I'm sorry, my lady; I don't know what that means." At first I couldn't believe she'd said that - the sheriff'll think she's a right numpty! But when you think about it, of course it was the right thing to do. What if she'd agreed to it without understanding what it meant? She'd have been acting outwith her instructions and probably would have been committing some kind of professional misconduct. Far better to admit it to the sheriff and feel a bit silly than admit what she'd done to the senior partner and feel a bit unemployed.
Legal jargon is tricky; that's just a fact. But do your best to get your head around it and soon you'll be explaining the difference between relevancy and specification as if it were the most obvious thing in the world. And if someone uses a funny phrase to you and you don't know what it means: say so!