Explainer should be held without bond for giving misleading information on how long a material witness can be detained. Previously, Explainer wrote, "Law enforcement officials can detain [a material witness] for a few hours without filing charges, but holding someone in custody for a long period requires formal charges."
It turns out, according to this section of the U.S. Code, that a material witness can be held as long as it is necessary to "prevent a failure of justice." This means that the people being brought in for questioning in the terrorist attack under material witness warrants can be held as long as a judge deems it necessary. One reason to hold material witnesses is that they are considered likely to flee the country. People being held as material witnesses have information important to a criminal proceeding and can be required to reveal that information. But they are not themselves charged with a crime and should be released once the proceeding is finished. If, however, a material witness becomes a suspect in the case, he can't be forced to testify against himself in violation of his Fifth Amendment right against self-incrimination.
Explainer, this time, thanks Carol Steiker ofHarvardLawSchool.