The POTUS should be competent, self thinking, and be able to think into long term effects to anything he signs (just to name a few) in my opinion.
Explanation:
In order for the POTUS to be the best for the country, they need to be the best choice for America. They have to not only be able to think for themselves but also think and consider the long term effects to anything they say, do, react, etc.
The Magna Carta was a government document that limited the power of the king of England and protected the rights of the nobility. It was written by the English nobility in 1215.