The legal definition of cyber space is the same as the internet, according to Duhaime's Law Dictionary. Cyber space is a decentralized communications network. According to the Department of Justice document Prosecuting Computer Crimes (see the link below), the jurisdiction of a cyber crime is often determined to be at the federal level because it involves interstate commerce. As the report states,
In the context of computer crime, the inexorable connection between the Internet and interstate commerce may sometimes be sufficient to satisfy the jurisdictional element of the statute at issue.
This means that if a detective uncovers a cyber crime or cyber terrorism, the case might have to be handed over to a federal entity, such as the FBI. Usually, if a computer used in the crime connects to the internet, that is sufficient grounds to substantiate that the case has interstate connections. In addition, the Patriot Act stated that acts that would constitute crimes in the jurisdiction of the U.S. can be prosecuted even if they are committed in foreign countries. That means prosecuting cyber crimes is not just like lassoing a cloud, as there are rules about jurisdiction that apply to these crimes.
Different states have different laws regarding cyber crime. For more information, see the state laws link below. Most state laws prohibit computer crimes, and different states require intentionality, meaning the crime is committed by intent. For example, in Massachusetts, computer crimes must be committed by intent. While states differ with regard to laws about cyber crimes, these crimes can be prosecuted under several different state laws or federal laws. Therefore, even if an act is not a crime in the state in which it was committed, it can be prosecuted in another state if the act is a crime in that state, or it may be prosecuted under federal law. Examples of cyber crimes include identity theft and hacking.
With regard to prosecuting these cases, the defendant generally must be tried in the state and district where the crime was committed. Still, even the Department of Justice report states, "applying the principles of venue to network crimes is not always a straightforward endeavor" (page 117). This is the problem in prosecuting cyber crime. The critical way to determine venue is to figure out where the crime was committed. For example, the report gives the example of a cyber crime case that began in California and used a router based in Arizona to break into a network in Illinois to get information in Kentucky. In this case, the prosecution could use the endpoints—California and Kentucky—or the states in the middle, as the venue for prosecuting the case, as venue can be “in any district in which [a continuing] offense was begun, continued, or completed" (page 118). To make a case for the venue being where the information passed through, the prosecutors should determine if the communications formed the offense. These are some of the considerations that go into determining if a specific detective has jurisdiction over a case.