No, not that law.
The The Law of Specificity. Which explains why you can swim a good distance at reasonable pace, but have trouble running, while you, on the other hand, can run "...three miles with no problem, but get out of breath after a few laps [in the pool]."
This Washington Post article explains it all:
When you practice a certain activity repeatedly, two key things happen: The primary muscles used in that task become more efficient at recruiting and using oxygen for the activity and (assuming your form progresses with practice) your mechanics often improve to the point where you are exerting less effort per stride, stroke, kick, racquet swing, mosquito slap, etc.Foiled again.
There's more. Read and learn.
In other news, you all know by now that the Complete Running Network has been re-incarnated, born again, and reinvigorated. Go, win a prize. Oh and don't forget to read all the cool posts while you are there. This site seriously rocks. (And, in the interest of full disclosure, it's entirely possible that I am in some small way connected with it. Blush.)