I stumbled onto the terrorism enhancement story several months ago while reporting on another one: the National Security Agency’s terrorist surveillance program. I learned about a trial of so-called “eco-terrorists” in Eugene, Oregon, part of the FBI’s Operation Backfire against the Animal Liberation Front and the Earth Liberation Front. After lawyers for the defendants for Daniel McGowan, whom I write about in the lead of my story, and his fellow defendants learned that the NSA was monitoring terrorist communications inside the United States without warrants, their lawyers wanted to know if the government had intercepted any of their clients’ information. Theoretically, if the government had used warranties wiretaps to secure their indictments–“fruit of the poisonous tree”–it could jeopardize the case. Prosecutors insisted they hadn’t used warrantless surveillance information, and for a time it seemed that the government would have to prove that to the judge. Fast-forwarding a bit, the matter ultimately became moot when defendants struck a plea bargain.

It seemed like the NSA angle wouldn’t pan out. But something else intrigued me. I learned that the prosecutors were pursuing a “terrorism enhancement” to the defendants’ sentences. I’ve been covering counterterrorism for six years, but I had never heard of this law, which is contained in the same part of the the U.S. Sentencing Guidelines that covers hate crimes and other “victim-related adjustments.”

Why was the government pursuing a terrorism enhancement against environmental activists? And who else had they sought it against? That question led me into a months-long investigation that culminated in my current feature story.

Just figuring out how many times the government had sought the enhancement proved impossible–the U.S. Attorneys Office doesn’t track that figure. But I was able to determine that judges have applied the enhancement at least 57 times in the past eight years. I studied more than half those cases–35–and learned that prosecutors sought the enhancement more often against domestic defendants, as opposed to members of international terrorist groups.