And as it is late and I cannot sleep, I wanted to comment on the UCC and how it informs this situation. The UCC was (as mentioned before) primarily created for large sales of goods, but it nonetheless applies to any smaller contract. It was meant to supplant the common law harsh rule that a “meeting of the minds” was required for every detail or else the contract would fail.
What the UCC does is provide “gap fillers” that is default rules where the parties neglected to provide specific terms in their written or oral agreement. It is really astounding the number of contracts that each of us enter into every day. You go to the convenience store and buy milk; that is a contract. And even in that little common contract, there are terms that are not orally made nor written but are defined by how we customarily or typically do things.
For example, I would make the offer of a milk purchase by going to the cooler and carrying it to the register. I don’t go to the clerk and ask if she is willing to engage in a milk purchase contract. Custom dictates that I take it to the counter. When I get to the cooler, there is probably a sticker below the shelf where the milk is located that says “$2.39.” I know that is the advertised price of the milk and not some random statement.
When I get to the counter, the clerk rings up my purchase and says, “That’ll be $2.39, please.” She doesn’t ask why in the hell am I putting milk on the counter. She knows from custom that I wish to purchase the item. Further, I either carried cash or a credit/debit card into the store to pay in USD. I know from custom that the store did not accept grains of silver or beaver pelts for milk, even though there was no sign on the door to that effect, nor was I informed by a store employee.
When I hand her $2.39 in cash or swipe a card, that is not a personal gift to the clerk or a donation to the store. That is my tendered payment for the milk. We know that through custom. If I handed a homeless guy $2.39 outside of the store, through custom we know that is a gift to the guy and not an invitation for him to go inside to buy milk.
These customs are all a part of the contract even though they are not written or orally communicated. However sometimes there are misunderstandings and under the common law, the contract would fail. But the UCC comes to the rescue.
Imagine the following. Your friend calls you on the phone and asks if you are in town. You say yes, and he asks if you would pick up his dry cleaning, bring it over to his house and he will pay the dry cleaning bill and you will have a nice dinner together that night. You agree.
You have entered into a contract. Both an extension of credit and a “food for picking up dry cleaning” contract. But how many terms were left out of the contract? How much credit are you extending? Did he dry clean a couple of shirts or is his whole wardrobe there? What is a “nice” dinner? Seven courses prepared personally by Gordon Ramsay including rare French wines and blini and caviar as a starter? Or is it his wife’s special roast beef? Somewhere in between? What if he throws a beef jerky stick at you? Again, you never talked about this or signed a written agreement.
What if he “repays” you by offering a shotgun, or Dutch Gilders, or beaver pelts? Must you accept?
If there is a material misunderstanding on any of these things, under the common law, the contract would fail. Under the UCC, there is gap fillers which rely on custom and reasonableness. Picking up dry cleaning would mean, under this legal regime, a reasonable amount of daily wearable clothing that he took to be cleaned, not his grandfather’s Civil War uniform. Repayment is in USD. For the dinner we use the UCC course of dealing and course of performance. Have you ate at his house before? Does he live in a mansion or a double wide? Is his wife a trained chef?
Long story short, this analysis informs Bob’s contract with the restaurant. The gap fillers in the UCC provide that his payment of leaving money on the table was a reasonable and customary method and therefore was a legal tender of payment. Unlike our dry cleaning contract, we have a clear and undisputed custom of paying a restaurant check by throwing money down on the table. That would inform a judge that such a payment method is a legitimate tender, and it becomes clear that such a payment is a good one. It is especially clear because the restaurant does not (or should not) have any misunderstandings about this term as they accept payment in this fashion all of the time. If they wish to protect against thieves, they can modify this contract term and require payment in person, much like my friend can explicitly tell me that his dry cleaning is the Civil War uniform or that the dinner is hamburgers.
Now, in almost 99,999/100,000 cases these things go off without a hitch and don’t see the inside of a courtroom. But law is made for special cases.