Theory or Law

We were discussing the difference between a theory and how it becomes a law.

Someone said that once a theory can be proven, it is then known as a scientific law.

So I then posed the question: "Does a duck have a mouth?"
The answer came quickly: "Yes!"

Me: "So then a duck's mouth is a Law?"
Again, the answer came quickly: "Yes!"

My reply was: "No, it's not, it's a bill."

Names withheld to protect the windowsill.