Already, the instantaneous availability of thousands of references within a few mouse clicks has dramatically increased the problem of academic plagiarism on high school and college campuses. Off-site students, especially those whose course require no real-time audio/visual participation, have no worries about an instructor suspecting that plagiarized work is different in quality or style from the student's in-person class contribution. The combination of online resources and the anonymity and remoteness element of online education probably increases academic dishonesty substantially.

On the other hand, remote online learning in certain courses of study and at high levels of study, and for certain types of students (such as post-graduate students, or those with particularly strong academic achievements and aptitude) undoubtedly adds valuable flexibility to educational opportunities. They may also be well designed for use in connection...

Naturally, any such on-site requirement would substantially reduce interest in online education, merely from the convenience perspective. Ultimately, online learning may be much like online availability within education more generally: both the Internet and online education are extremely beneficial to honest, motivated students; and they both may be easily corrupted for academically dishonest use.
References

Li, C, and Irby, B. "An overview of online education: attractiveness, benefits, challenges, concerns and recommendations" College Student Journal; Jun/08.

Trotter, A. "Voluntary Online Teaching Standards Come Amid Concerns Over Quality"

Education Week; Mar 5/08.