They vary form state to state creating some confusion. In the former, everyone is required to be asked whether they want to donate. If there is no response, it is assumed they do not want to donate. In required refusal, it is assumed that everyone wants to donate unless they refuse. Therefore no response is a tacit approval for donation.
Opponents argue that only a minority actually do.
Many states have now done exactly as Mr. Conway suggests by requesting a decision at the time of driver's license renewal. This process is usually easy, and affords people repeated opportunities to make their wishes known.