I'm assuming you're referring to the JobRoller theme since you mention a job seeker? (Please clarify if this is not the case). JobRoller by default does not have an option to allow anyone other than the admin to assign a job listing to a specific user, so your requirement for others to "accept" a listing/case is not something built into the theme.
I may be off the mark with what you're actually trying to achieve, but perhaps it may be worthwhile to look at the
Quality Control theme, which is an issue tracking software, and perhaps may follow more of the process required for what it sounds like you are looking into?
