We would like to be able to halt the progress of an individual using an application or other form that does not apply to them. Our primary use case is that we use a different application form for prospective international students vs. US citizens, but there may be many other scenarios in which this is needed. (See screenshot below, in which the applicant is instructed to discontinue filling out the application if they are not a US Citizen, but there is no way to prevent their clicking the "Continue" button as long as they answer the question.)
We can even make all subsequent pages & questions conditional to the screening question, but the applicant can still proceed to the end of the blank application and submit. (See below a dummy application in submitted status even though it is invalid).
In these cases, we would delete the invalid application and assist the applicant with starting the correct form, but it would be better to be able to block such submissions in the first place.
So, the request is for the option to make a form's Continue and/or Submit button(s) conditional upon the response to one or more fields on that form. Thus, we would be able to set up our application for US Citizens in such a way that if the response to "Citizenship" is not "United States of America," the "Continue" button does not appear (or it could simply remain inactive... either way would suit our needs).