The general rule in contract law is that both sides must give some consideration for the contract to be valid. However, there are some exceptions. For example, in the case of Carr v. Maine Central R.R. (78 N.H. 502, 102 A. 532 (N.H. 1917)), Carr was overcharged for freight hauled by Maine Central Railroad. Maine Central admitted the error, but claimed that they could not refund Carr’s money until they filed paperwork with the Interstate Commerce Commission (ICC). Under ICC regulations, there was a limited timeframe to authorize a refund. Maine dragged their feet until the time expired, and then told Carr that they couldn’t refund his money. Carr sued. Maine Central argued that they were never contractually obligated to file the paperwork. However, the Trial Court found that even though Maine Central was not obligated to file paperwork, once they agreed to do it, they were legal liable to do it, even though there was no consideration given to them by Carr.