Causa sine qua non
An elegant Latin phrase meaning the effective cause of a given event: literally, the “cause without which there would be nothing”. It is a question you might turn your mind to when considering causation and remoteness of damage following negligence or breach of contract.
Where there are several contributing factors to some kind of perfidy, lawyers will often be obliged to identify which ones are suitable subjects for legal warfare. The causa sine qua non is just such a subject.
An example[1] will suffice.
A inhouse lawyer has been out to a law-firm cocktail function and crossed that imperceptible threshold — the Schwarzschild radius of alcohol consumption — beyond which the discretion, judgment and common sense which would usually guide him safely home to bed in time for work in the morning ceases to operate. He finally makes it back to base at 4 a.m., he knows not how.
As luck would have it, he has already arranged to be late into the office the following morning, so he can attend his daughter’s school assembly. The theme is to be gender equality in modern Britain, but there will be a brief interlude for a song about spiders.
Amwell J peers over his glasses down at counsel before him. Now, is the school assembly the causa sine qua non of his absence from that dreary 9 a.m. meeting?
If it pleases your honour, I humbly submit it is not.
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