Readers send me examples of bad things. I shudder and pass them on, so you will never commit the same grievous faults.
You keep something or someone at arm’s length in order to ensure independence or impartiality. Note that apostrophe (and its placement; arms’ length is justifiable but not preferred).
If you want to turn the phrase into an adjective, you’ll need to add a hyphen (even if you think that looks a bit over-punctuated): an arm’s-length transaction.
A French-Canadian boss of mine always pronounced it harm’s length, which had a certain unintended logic to it.
The instant case
This would have been normal, current English in the late eighteenth century, but it has no place in your present-day factum or pleadings.
Say this case (and NOT the case at bar, which always makes me think of cocktails).
Bad enough as a noun, worse as a verb.
The noun just means something like connection, contact or common ground; the verb (especially as used outside the IT context) is a silly way of dressing up old-fashioned words like meet or talk.
Recently seen, as though we still drafted documents with quill pens by candlelight.
Archaic compounds like whereupon can always be expressed in clear, modern language that won’t make you look like a pompous old fogey.
Replace this one with something like at which, on which or just plain then. Your readers will be grateful.