Interestingly googling around the principle usage -- to mean pertaining to a tort -- of this spelling is in UK Terms of Use. It's quite hard to search though as often people will talk about tortuous caselaw [1], meaning 'twisting and turning'. Both usages can be in the same document, so Google Search - in particular - is no good here.

Spelling "tortuous": I find supporting documents from the UK Home Office [3], the UK IPO (including in court proceedings for trademark), and in private practice references to UK tort law, eg [2] dated 2019.

I don't consider my usage to be wrong per se but will consider using tortious in international forums (I so wanted to write "fora", lol); thanks for the query, terse as it was.

It's possible we're all using it "incorrectly" of course. I work in the IP sector, we might all be drinking from the same fountain (eg perhaps reading past UK caselaw keeps us archaic).

[1] https://www.worldtrademarkreview.com/brand-management/signif..., example of talking about an intricate case that twists and turns.

[2] https://thelawreviews.co.uk/edition/the-intellectual-propert... talking about an infringement of a tort, as tortuous.

[3] https://www.gov.uk/government/publications/references-to-the... , note I'm assuming the Home Office is the origin, it's Gov, but I don't really see mention of the department that owns that data.