The Michigan Supreme Court has ruled that a defendant who plotted a massacre at his Detroit-area high school won't be sentenced to a longer term for making terrorist threats.

The case involves Andrew Osantowski, who in 2004 sent messages to an Internet chat room saying he might kill fellow students at Chippewa Valley High School near Mount Clemens. Osantowski was convicted of threatening an act of terrorism and using a computer to threaten terrorism.

The dispute is how to calculate his sentence, and potentially future defendants, charged with terrorist acts. The case appears to have been one of the first in the country to apply anti-terrorism laws to threats of school violence.

The court ruled 5-2 that not all threats are acts of terrorism.