Some critics have alleged that use of this proprietary software violates educational privacy as well as international intellectual-property laws, and exploits students' works for commercial purposes by permanently storing them in Turnitin's privately held database.

[1] Turnitin, LLC also runs the informational website plagiarism.org and offers a similar plagiarism-detection service for newspaper editors and book and magazine publishers called iThenticate.

Other tools included with the Turnitin suite are GradeMark (online grading and corrective feedback) and PeerMark (student peer-review service).

In addition to student papers, the database contains a copy of the publicly accessible Internet, with the company using a web crawler to continually add content to Turnitin's archive.

[18][19] Lawyers for the company claim that student work is covered under the theory of implied license to evaluate, since it would be pointless to write the essays if they were not meant to be graded.

The company's lawyers further claim that dissertations and theses also carry with them an implied permission to archive in a publicly accessible collection such as a university library.

[20] University of Minnesota Law School professor Dan Burk countered that the company's use of the papers may not meet the fair-use test for several reasons: When a group of students filed suit against Turnitin on that basis, in Vanderhye et al. v. iParadigms LLC, the district court found the practice fell within fair use; on appeal, the United States Court of Appeals for the Fourth Circuit affirmed.

[22] Some students argue that requiring them to submit papers to Turnitin creates a presumption of guilt, which may violate scholastic disciplinary codes and applicable local laws and judicial practice.

[32] Nearly a year later, Judge Claude M. Hilton granted summary judgment on the students' complaint in favor of iParadigms/Turnitin,[33] because they had accepted the click-wrap agreement on the Turnitin website.

Besides, more sophisticated machine learning techniques, such as automated paraphrasing, can produce natural and expressive text, which is virtually impossible for Turnitin to detect.

Asked about the situation, the then vice president of marketing at Turnitin Chris Harrick said that the company was "working on a solution", but it was "not a big concern" because in his opinion "the quality of these tools is pretty poor".

The article then listed a few possible "tricks" and how Turnitin intended to take care of them, without mentioning scientific literature, technical treatises or examples of source code.

[41] In 2009, a group of researchers from Texas Tech University reported that many of the instances of "non-originality" that Turnitin finds are not plagiarism but the use of jargon, course terms or phrases that appeared for legitimate reasons.