Should a juror be allowed to “friend” a defendant, a plaintiff, a witness or anyone else involved in the case on Facebook during a trial? The courts emphatically say no.

The challenge for courts is enforcing social-media bans during trials, which can last for weeks. And lawyers increasingly are using jurors’ forbidden posts as a reason to appeal convictions and acquittals.

Typically judges will instruct jurors not to do any independent research or communicate with anyone about the case they are hearing, either through social media or in person. Courts are concerned that what people say online could be construed as having a bias about the case. It could also reveal information about a trial before it becomes public.

According to the Wall Street Journal, a Texas man was recently sentenced to two days of community service for “friending” a plaintiff in a car-wreck case. A Florida juror was held in contempt and sentenced to three days in jail last month after he used Facebook to “friend” a defendant.

A recent Pew Research Center survey showed about two-thirds of adult Internet users say they use social-networking sites such as Facebook and Twitter.