Read this:

If the Deposit is not paid, the Seller has the right to rescind this Agreement by a notice in writing to the Purchaser delivered within 30 days from the date of this Agreement, provided that such rescission right shall not be effective unless and until the Seller does not rescind the Preliminary Agreement for the Property.

Got it? If not, feel free to read it again. And again… and probably again.

Got it now? Perhaps you should read it once more just to double check.

No doubt you’re having trouble with this part: “…shall not be effective unless and until the Seller does not rescind…”

I think you’ll agree that the difficulty is mainly due to the use of multiple negatives – “shall not”, “unless” and “does not”. It’s more of a brain teaser than a practical piece of communication. Unfortunately most of us don’t have the time or inclination to work out brain teasers.

So – my advice is simple: Don’t use multiple negatives. Write something like this instead:

If the Deposit is not paid, the Seller has the right to rescind this Agreement by written notice to the Purchaser delivered within 30 days of the date of this Agreement. However, the rescission right is not effective if the Seller has rescinded the Preliminary Agreement for the Property.

I know I’m taking something of a risk pretending I’ve understood the original correctly, but I’m willing to do so. If my interpretation is wrong, far from showing my lack of intelligence, it proves how bad the writer is at communicating.

In case I haven’t convinced you that multiple negatives are a bad idea, here are a few more brain teasers for you to waste your time on:

The following actions are not excluded from the prohibition.

No termination will be approved unless the administrator reviews the application and finds that it is not lacking in any requisite materials.*

No reason for refusing confirmation of the master’s report not covered by the exceptions in the rule is disclosed by the record or urged by the defendants.*

* From Bryan Garner, Legal Writing in Plain English, University of Chicago Press, 2001, p. 31