I don't see how notifying the current employer of the applicant before deciding on giving the applicant an offer IS A GOOD IDEA.

You're basically sabotaging the applicant. What if he took MC for the interview? Or what if he's handling a project and deadline is half a year away? Employer will give him a hard time and end up stuck if there's no offer at the end.

The proper way is to notify the current employer AFTER the candidate ACCEPTED the offer. I believe there are clauses to terminate the offer if any info was found not true. The information that he wants to leave should always and only be announced by the applicant himself.