Ne explétif after sans que

Question

With respect, are D.G and Cécile’s posts right? Surely ne is only needed after sans que when the verb preceding it is negative, and then only in more formal French. So "Tu as fait tout ça sans que Neve soit au courant" will not require a "ne".

The linked lesson could be a little clearer, but says:

If the main verb is NOT used with negations, then you CANNOT use the ne explétif.

If the main verb is used with a negation, you can use the ne explétif, but it is considered optional

Cécile Janty-Davies · Accepted Answer

Bonjour Anne, 
Thank you for pointing this out, I have altered my answer to D.G.
This is what our little AI helper says about using 'sans que', which you might find interesting -
" With "sans que" (without), you do not use the "ne explétif" in the following clause, regardless of whether the main verb is positive or negative.
"Sans que" always takes the subjunctive in the dependent clause, but it never requires the expletive "ne" because it already contains the negative meaning within itself.
Examples:
"Il est parti sans qu'elle le sache" (He left without her knowing) "Je ne peux pas partir sans qu'il soit d'accord" (I can't leave without him agreeing)
This is different from expressions like "avant que" or "à moins que," which can take the expletive "ne" in formal/literary French. With "sans que," the negation is already built into the conjunction itself, so adding "ne" would be redundant and incorrect.
 
The key is remembering that "sans que" = "without" already expresses the negative idea, so the subjunctive clause that follows should be purely positive in form."
Hope this helps!