Answer:
Mechanic's Lien
Explanation:
The answer is a "Mechanic's Lien." A Mechanics Lien forces the client of a company to face the payments directly if he or she hasn't paid for the services they hired. In this case the City Architects using a Mechanics Lien forces John and lets him know that he needs to pay the architects for the work done on his home in a attempt to reclaim the money owed.
Hope this helps.