The clause has been used by the u.s. congress to criminalize the production and use of medicinal marijuana even in states where the growing and use of homegrown marijuana for medicinal purposes was legal.

Commerce (clause).

Explanation:

The commerce clause gives power to the United States Congress to regulate commerce among the states. That's why, in  the exercise, it's explain how the US Congress was able to criminalize the production and use of medicinal marijuana even in states where the medical purpose of it was legal.

Answer is in the file below

cutt.ly/rzNrBcz