Comma before "which"

I am editing a court transcript for a class (cannot alter the text). For each change I make, I need to cite a rule for it. I have read a lot about the use of which and that, and I am still confused on this sentence.

I feel that it needs a comma before which, but I am unsure what the “official” reasoning would be. I know that, normally, that should be used for restrictive clauses, and which should be used for non-restrictive clauses, but I am unsure if it was spoken correctly.

Or is it because there is only one Exhibit 2, making the which clause non-essential (non-restrictive), and therefore a comma is needed?

We’ve put in front of you Exhibit 2 which is a Visa statement of account.

Solution 1:

In your example, which is a Visa statement of account looks like a supplementary (non-restrictive, non-defining) relative clause, although it would be necessary to see the wider context to be sure. If it is, then a comma before which would be appropriate for that reason.

For more on which and that, see here.

Solution 2:

For many English writers (nobody knows how many, but at least a substantial minority -- or maybe a majority -- of the best ones), comma usage is not a matter of grammar, so which word is used is irrelevant -- rather, it's the intonation of the spoken words that counts.

These English writers use commas to indicate intonation dips. And many English readers interpret them that way. Certainly I do.

So the rule is to listen to the transcript of the speakers' voices, and put in commas according to their intonation.

Failing that, any insertion of commas into a text-only legal transcript is altering the document, since it offers the judgements of the editor instead of the transcriber.