Most criminal cases involve violations of state laws and are heard in state court. When a person is charged by the U.S. Attorney’s Office of violating federal law, the accused has the added misfortune of being prosecuted in federal court. While county District Attorney’s Offices tend to prosecute whatever the local and state police departments bring in on arrest, U.S. Attorney’s Offices and federal investigators pick and choose which offenses warrant their attention and considerable resources. Presently a high amount of energy is put into the prosecutions of “illegal reentry” cases (people who have been deported or removed from the US who have reentered illegally.) In Boston, most federal cases involve the sale of drugs and guns.
Some acts are crimes at both the state and federal level. For example, a person selling drugs in Boston could himself charged with distribution or trafficking in the Boston Municipal Court or Suffolk Superior Court, but could also be charged as part of a drug conspiracy in federal court. While drug distribution sentences in MA state courts are harsh, they pale in comparison to their federal counterpart. Do not assume that just because someone is charged with drug crimes in federal court that s/he is a serious offender. Federal investigations often sweep up minor players with the hope that those individuals will provide information against those with leadership roles in the conspiracy. While there are considerably more illegal acts under state law than under federal law, there are some crimes that exist in federal court that do not have a MA state court counterpart. Among them are mail fraud and tax evasion. A less obvious and known example is cyberstalking which has been criminalized by a federal statute but there isn’t a specific state level equivalent (although the offender could face charges such as criminal harassment.)