A few bad apples can spoil the whole barrel, it's said; and in the foreign-student context, a few unethical schools are apparently making life difficult for all F-1 students.
The highest-profile case of late was Tri-Valley University, in California, which was raided by federal agents in January of 2011 and prosecuted as a "sham" university. The U.S. government alleged that Tri-Valley made money by bringing in foreign students who, rather than attending class, spent much or all of their available time employed across the United States.
U.S. immigration law places strict limits on the amount of time that F-1 foreign students can spend engaged in employment, and requires them to obtain work permits in many situations. See "When F-1 Students Can Work in the U.S." for more information.
Not surprisingly, U.S. Citizenship and Immigration Services (USCIS) is now reportedly stepping up its enforcement efforts, looking for schools that fit a similar profile to Tri-Valley's. If and when USCIS finds similar violations, the U.S. government may not only take action against the school, but deny visas or continued status to the students – and in the worst-case scenario, put a finding of fraud or misrepresentation on a student's immigration record. The latter action will result in the person becoming permanently inadmissible to the U.S. – that is, ineligible for any future visas or green cards (without first obtaining a "waiver," or legal forgiveness).
One of the easiest red flags for U.S. immigration authorities to identify is when a student takes a heavy proportion of classes online. The underlying reasoning is pretty obvious – if the student doesn't need to show up in the classroom, why would he or she need an F-1 visa and U.S. entry in the first place – unless perhaps it's to spend an illegal amount of time earning U.S. dollars?
U.S. immigration regulations actually specify that an F-1 student can take no more than one online class, or three credits' worth, each academic term, and none at all if the student is in a language program. (See 8 C.F.R. Section 214.2(f)(6)(i)(G).)
What is an "online" course, anyway, given the range of technological options? USCIS defines it broadly, as "a course that is offered principally through the use of television, audio, or computer transmission including open broadcast, closed circuit, cable, microwave, or satellite, audio conferencing, or computer conferencing." In practical terms, USCIS views this to mean pretty much any teaching situation other than one in which students and teacher are in the same physical space at the same time for instruction. So even if the students are all in one place and the professor appears via Skype, or it's a "simulcast" course, USCIS may dub this an "online" course.
If you are a prospective F-1 student considering schools in the U.S., watch out for schools that don't seem to have an international reputation – or that actually have a reputation among foreign students as a place where it's easy to spend most of one's time earning money. And if you're already in school, avoid classes that have a heavy online component; or talk to a lawyer about your situation and any concerns about your school.