Misleading by omission: Can we omit a key ingredient?

I recently was asked about the ethics of this situation. Where it is a secret family recipe, can you preserve its sanctity by omitting a key ingredient?

Our conversation then moved on to how this might play out in our professional sphere. I am an ethics solicitor and find my conversations often move in this way.

Can we omit a key ingredient professionally? This is where we are in the tricky area of misleading by omission. There are situations where an omission is simply dishonest. We present something as full and complete when it is not.

But what about situations where we fail to point out that someone else is mistaken. Instead, we sit silently by. Is that ethical?

This is where Conduct Rule 30 comes in. It says we must not take “unfair advantage” of someone else’s “obvious error” to obtain a benefit that has “no supportable foundation in law or fact”. This rule has uncertainties. What is “unfair”, “obvious” or “supportable”? However, I feel that often those uncertainties can be removed by approaching it from the perspective of misleading. If we say nothing, are we implicitly agreeing with the erroneous position? Are we positively misleading by omission?

And then we can add to that situation if it involves obligations to the court and the administration of justice. What if it is the court that is making the “obvious error”? As officers of the court, we are then doubly obliged not to mislead by omission.

As for the recipe, from my own disastrous attempts at cooking sponges, I doubt any omission would actually make much difference, but that is not the ethical point. Make sure your recipe is complete and your friend’s sponge has the best possible chance of fluffiness.