Statement of Truth how serious?

[atticus]

Earl, what we are getting at is this.

Instead of saying:

That's a lie! You've committed perjury!

You should say:

I think you are mistaken, for these reasons ...

If you accuse the other party of dishonesty, you make the mountain you have to climb rather higher.

In many cases there is rarely a slam dunk question and answer. Usually it is a question of putting enough pieces of the jigsaw together to show the picture. I have read so very many judgments in which the judge says "Mr X was a truthful and honest witness, but his evidence was mistaken in that ... "

[Earl]

Sorry atticus, just read your last post which was over the page, another 'rookie' moment. But I'll leave what I've just written in case it gleans me a bit more knowledge. Thanks for your help.

Trying to get my head around the comments, and I don't care if you call me a rookie, with rookie errors. It is a learning curve.

My case has a history of decades to the present day. The defendant denies saying or doing things, and these cannot be proven. so he denies.

In the next sentence he offers a statement that can be disproved with physical evidence. So to me its a lie. He has used that word in his statement so why shouldn't I, and I add the proof of the lie.
Therefore, (rookie believes) his testimony should be doubted. (I do get you can lie in some parts and still be believed in others).

By what you are saying I should not use the word lie but mistaken, and let the judge judge. Even if I have 100% proof of the lie, say mistake?
An example, he states he paid my mortgage off in say 1995, but in 2015 I still have a mortgage and documents that prove when it was taken out and documents to prove I still have it. So what he says is a mistake!
He is trying to make out he's a great guy. So he says he bought land, built a building for 'x's' use, however planning application and Land registry say differently. 'x' bought it and developed it. So his statement lie or mistake.
Going back to read your posts again.

[atticus]

Incorrect. That is all you need say.

Not "that's a lie", but "that's not right [and here's why]".

[Earl]

O.K
But it was nice for a bit going for the jugular.