Where the 17C Formula Came From The 17C formula traces back to a 2001 Georgia Supreme Court case, State Farm Mutual Automobile Insurance Company v. Mabry, in which more than 25,000 claimants sought payment for vehicle value lost after repair. The court confirmed that insurers were obligated to pay diminished value claims under their policies. … Continue reading 17c Formula, Unfair for Diminished Value Calculations.