A Memo from ICE confirming SEVP’s guidance on unpaid employment and noting some OPT STEM extension applications were erroneously denied by USCIS because applicants had or intended to work in volunteer or unpaid intern positions is attached. The ICE Memo confirms:

A student may work as a volunteer or unpaid intern, where this practice does not violate any labor laws. The work must be at least 20 hours per week for a student on post-completion OPT. A student must be able to provide evidence acquired from the student’s employer to verify that the student worked at least 20 hours per week during the period of employment.

USCIS Student OPT Public Announcement