Many have argued that technologies used to protect copyrighted works usually go beyond the letter of the law and subsequently impinge on interests relating to freedom of information and expression, privacy and free choice. Classic examples are technologies that prevent CDs or DVDs from being accessed or copied under certain conditions, or that block or filter-out copyright-protected materials. This article assesses digital text-watermarking, which does not restrict users’ access to or use of works, but individualises every user’s copy by changing the formatting or words in a text (e.g. “not visible” for “invisible”). Every purchaser/user receives a unique version of the work, meaning that, if there is any illegal upload or usage, it is possible to determine which user the copy came from. The technology thereby allows legal (and illegal) use to be undertaken, but serves as a tool for enforcement when there is illegal use. This article assesses digital text-watermarking from a comparative law perspective, particularly the Civil Law and the Common Law traditions.