Which country was the first in the world to incorporate the protection of the environment into its constitution?

Namibia

Explanation:

The nation implement the protection to protect the destruction of its high plateau and desert along coast.

They implemented the protection in its constitution after their independence in 1990. (Even though other countries already made some acts to save the environment, Keep in mind that the previous efforts made by other countries are only bills, not the same as constitution)

answer; john stuart mill's principle of utility is your answer; /// good luck