Dr Pepper sues Coca-Cola for $750,000 for monopoly attempt (1951)

In January 25, 1951, Dr Pepper filled a $750,000 million dollar lawsuit against Coca-Cola. This lawsuit didn't come out of nowhere, Dr Pepper filed the lawsuit due to Coke's 5 cent (per bottle) price tag in Chicago. The suit states that Coke has been pressuring store owners (in Chicago) to sell Coke for 5 cents, causing Dr Pepper to lose $250,000 from lowering it's soft drink to meet Coke's standard low. However, Coke had been selling bottles for 10 cents each outside of the Chicago area.

Adjusted inflation:

Sources: The Real Pepsi Challenge by Stephanie Capparell, Chicago Tribune archives, Inflation calculator.

Note: NY times also has an article on this lawsuit, but you'd have to buy it. New York Times article