The challenge of creating the smallest possible law to protect the freedom of trade from potential erosion by politicians is to ensure that it's both concise and comprehensive. Here's a minimalistic attempt:


Ultimate Trade Law:

"Trade freely, without harm or deceit; any interference faces correction."


Explanation:

This law emphasizes the freedom of trade while ensuring ethical practices and deters any potential interference. It's designed to be self-emergent, meaning its principles should naturally arise and adapt over time to protect the essence of free trade.