I'm working on a project currently where the client organisation deals with vulnerable people regularly. This has resulted in the weird situation where 1) they're really obsessive about legal acknowledgement of things, as they don't want to be sued; and 2) everything has to meet accessibility compliance guidelines. 

After talking them out of using DocuSign—yes, they actually wanted users to physically sign a copy of the site's terms and conditions—we've 'settled' on a situation where the user must scroll x% of a scrollable div before they're allowed to click an 'I accept' checkbox and proceed. They've also requested some *very* clear copy intended to explain this to users (e.g. "Please scroll through the terms and conditions and check the box in order to accept them".)

I have some concerns with this. 

1. This seems like a miserable experience for screenreader users; who have to go through each line of the terms one by one to scroll the container far enough to reach the defined percentage.
2. This approach would be incompatible with any assistive technologies or user stylesheets that disable or alter the display of the scrollable area.
3. The terms are marked up as part of a form, and I'm aware that many screenreaders have a 'form mode'. Would this mode cause the user's interactions with the scrollable area to differ (e.g. skipping over the text entirely to progress to the next form field)?

Any help belaying these concerns, or alternatively talking a client out of a bad idea, would be appreciated. Thank you.