The Espionage act of 1917 was a law passed by Congress that made it illegal to share information or interfere with the United States during a war. This meant it was illegal to spread false reports or rumors that could hurt the war effort, or to interfere with military or naval forces. Anyone who disobeyed the law would face jail time or a fine. The law was used during World War One to stop people from saying or doing things that could hurt the United States or the war effort.