opt-in and opt-out

日本でもこの十年程で個人情報の取り扱いに関しては厳しくなってきましたが、NUDGE by R. H.Thaler and C. R. Susteinに学生の名簿を兵隊の募集の為に軍に渡す云々の事が書いてありました。
However, the law stipulates that "a secondary school student or the parent of the student may request that the student's name, address, and telephone listing not be released without prior written parental consent, and the local educational agency or private school shall notify parents of the option to make a request and shall comply with any request." Some school districts, such as Fairport, New York, interpreted this law as allowing them to implement an "opt-in" policy. That is, parents were notified that they could elect to make their children's contact information available, but if they did not do anything, this information would be withheld.
上に出てきた "opt-in" の対語 "opt-out" もこの後に出て来ます。
Both the Defense Department and the school districts realized that opt-in and opt-out policies would lead to very different outcomes.
Wiktionaryに "opt-in" と "opt-out" の説明が次ぎの様にありました。
"opt-in": Of a selection, the property of having to choose explicitly to join or permit something; a decision having the default option being exclusion or avoidance; used particularly with regard to mailing lists and advertisement.: They set up an opt-in mailing list, so that those who wanted the notices could subscribe.
"opt-out": Of a selection, the property of having to choose explicitly to avoid or forbid something; a decision having the default option being inclusion or permission; used particularly with regard to mailing lists and advertisement.: With opt-out forms, take care to uncheck all unwanted selections.