Ralph, a Canadian manufacturer, agreed to supply 10,000 paving stones at a price of $1.50 CAD no later than January 25, 2021 to Bob's Construction Company located in Seattle, Washington. At the time the US Dollar was at par with the Canadian dollar.

Before delivery the CAD plummeted by 20% thereby wiping out Ralph's profit margin.Ralph called Bob who agreed to pay an increased price of $1.80 CAD per stone (ie 20% increase). Ralph delivered the stones on time and invoiced Bob's Construction at $1.80 per stone. Bob paid $1.50 per stone.

Ralph sued Bob's Construction for the difference.

1. Is there a contract for $1.80 per stone?
2. What is the Rule of Law