Among other things, the 6th Amendment guarantees defendants the right to an impartial jury. Seems simple enough. But what if a case is so high-profile or notorious that everyone in the vicinity has heard the details, and it becomes impossible to find potential jurors who haven’t already drawn conclusions about the defendant’s guilt? In that situation, a lawyer can file a motion for a change of venue.

If a change of venue motion is granted, the trial will be moved to another jurisdiction. If the defendant is being prosecuted under state law (as most are), the case will end up in another county in the same state. If the case is being prosecuted by the feds, the case will move to another state.

There’s a strong reluctance within the justice system to grant changes of venue. One reason for this is that the 6th Amendment states that the jury should be “of the state and district wherein the crime shall have been committed.” More practically, however, changing venue is expensive. The entire legal teams for both sides have to travel and temporarily relocate, as do witnesses. And the defendant will need to be transported, usually along with a lot of police.

Sometimes, though, it’s going to be nearly impossible to constitute a fair jury. This is sometimes demonstrated by the requesting party via public opinion polls or other research showing high local levels of knowledge about the case and showing that most locals have already drawn conclusions about the defendant’s guilt.

Either side can request a change of venue. It’s far more often the defense who files this motion, but the prosecution can as well. Very recently, for example, the prosecutor moved for a change of venue for a white University of Cincinnati policeman charged with murdering a black man.

You may be familiar with some famous cases in which changes of venue were granted, such as Timothy McVeigh (the Oklahoma City bomber) or the LAPD officers in the Rodney King case. Nevertheless, granting these motions is a rare thing.

Even in high profile cases, judges will deny change of venue motions if they believe it’s possible to obtain a fair jury, or if they believe the case is so notorious that moving it won’t do much good. When Boston Marathon bomber Dzhokhar Tsarnaev was tried in 2015, for instance, the judge refused to move the case.