There's a lot of confusion over this rule.
Almost all of the time a J1 Exchange visitor will not be subject to this rule - you can check however by looking at the bottom off your previous DS-2019 to see if the conslar officer has ticked the box.
The 212(e) rule is DIFFERENT however from the repeater rules above - just because you are not subject to the 212(e) rule does NOT mean the above rules don't apply!
You may be subject to the U.S. government’s home country physical presence requirement (section 212(e) of the U.S. Immigration & Nationality Act). This requires participants to return to their home country for a minimum of two years before returning to the U.S. on certain types of visas. (H, K, L and legal permanent resident) though usually not another J-1 visa. If you are subject to 212(e) it is advisable to contact the embassy to confirm your eligibility for another J-1 visa program.
Participants are typically subject to the requirement because of one of the following reasons:
Their field of training is on their country’s Exchange Visitor Skills List (see below)
The participant received government funding for their program
This requirement is applied at the sole discretion of the Consular Officer performing your visa interview. They will mark it on your J-1 Visa and DS-2019. They should also inform you of the reason why you are subject to the requirement. For more information see here.