In examining the U.S. (Federal) “Law(s) of Terrorism” as part of the Criminal Justice venue, let me first and foremost point out that the United States’ legal approach to the investigation and prosecution of terrorism predominantly involves the discovery of predicate crimes which count toward conspiracy offenses comprising the “material support of terrorism”.
Apart from that, there exists very little organized legislation that anyone might reference as the “law of terrorism”. In the U.S., typical perpetrators are not usually charged with terrorism, but rather with other offenses predominantly criminal in nature.
Accordingly, under U.S, law, there exists a relatively long-standing legal code cited as Title 18, Part I, Chapter 113B, Section 2331, which is entitled "Terrorism". While this is an attempt to define terrorism, it is essentially America's version of outlawing ruinous and destructive conflict intended to protect from international conflicts that spill over onto American soil.
We also must remember that physical jurisdictions are important within the law of terrorism, as they similarly are in law itself. Within the context of the U.S. Constitution, it is not illegal to claim that you are a terrorist, belong to a terrorist group, or, be suspected of being a terrorist.
Instead, ninety (90%) percent of the time, suspected terrorists do nothing wrong until they commit an indictable act. The exceptions to this are what the criminal justice system refers to as the "suspect," the "person of interest," or, the "unindicted co-conspirator."
In the great majority of cases, however, indicted terrorists are charged with crimes (in lieu of “terrorism”) such as planning for violence, raising funds illegally, and, conspiring to carry out a violent act. The most common criminal charges initially lodged against terrorists include bombing, arson, hijacking, assault, kidnapping, murder, theft and sabotage.
And, with regard to terrorists who are captured before completing an act, the most common charges are the illegal possession of explosives, the illegal possession of weapons, the illegal raising of funds and conspiracy.
In contrast to all of the Federal-level laws, U.S. State-level criminal laws customarily only recognize “specific-intent crimes”, such as telephone harassment for terrorist purposes, along with other stalking and domestic violence offenses. However, these are not really referring to terrorism, but rather to forms of personal intimidation.