Final Answer:
A U.S. citizen who posts material on the Web that is illegal in a foreign country can be prosecuted if he subjects himself to the jurisdiction of that country.
Step-by-step explanation:
The concept of jurisdiction refers to the authority that a legal body or government has to apply and enforce its laws. In the context of the question, the term "jurisdiction" is crucial in understanding the circumstances under which a U.S. citizen could face legal consequences for posting illegal material on the Web in a foreign country.
When an individual willingly exposes themselves to the laws and legal processes of another country, they subject themselves to that country's jurisdiction. Jurisdiction is not limited to geographical boundaries but extends to individuals who voluntarily avail themselves of the legal framework of a foreign jurisdiction. This can occur through physical presence, business activities, or, in the digital age, by engaging in online activities that fall under the legal purview of a foreign nation.
In the scenario described, if a U.S. citizen posts material on the Web that is deemed illegal in a foreign country, and if they, in some way, subject themselves to the legal authority or processes of that country, they may be prosecuted. This underscores the complex legal landscape of the internet, where actions taken in one jurisdiction can have legal implications in others, emphasizing the importance of understanding and respecting the laws of the countries involved.