How did the Lemon law get its name?

That's easy! The name is derived from the items in which it covers; "lemons!"

Though, these aren't any ordinary lemons, the "lemon" in which the Lemon Law applies to are generally expensive, complicated pieces of machinery that are sold as a perfect working device, but proves to be defective after purchase, such as an automobile. While cars are the most common things referred to as a "lemon" (besides the fruit of course!), it also applies to other items, such as a home washer or dryer, refrigerator, and more!

Now, why did they choose the name "lemon"? Because it "leaves a bad taste in your mouth!"