Technically all Wikipedia editors are outside their field since they are all generally anonymous. That leaves common sense which is generally described in WP:NOTABLE.
That is a remarkably illogical non-sequitur. Being anonymous does not imply that one loses all connection with his fields of interest.
No, it means that it is not verifiable.
I've invited experts in their field to contribute their expertise to Wikipedia, only to have it vetoed by an anonymous editor who claim to be a professor and an expert in his field.
You would think that two verifiable experts in their field would have sway over an anonymous unverifiable editor.
Regards, Ian Tresman