Senate Bill 0186 (Public Act 4 of 2021) - Summary of Changes (3/25/21) The regulatory requirements for cultivating industrial hemp in Michigan are prescribed in the Industrial Hemp Growers Act, Public Act 220 of 2020. This law has been updated via Senate Bill No. 186 (now Public Act 4 of 2021) to reflect the changes made in USDA's final rule. The updated PA 220 of 2020, as amended, has been published.