Evan Kohlmann is a private consultant who has studied Al-Qaida and other terrorist organizations. He has previously testified 17 times as an expert witness at federal trials of accused terrorists.
Working at the behest of prosecutors, Kohlmann wrote a report concluding the eight men fit the profile of a homegrown terrorist cell.
Kohlmann only reviewed evidence provided by prosecutors and has had no direct interaction with the accused. Defense lawyers argued Tuesday he should not be allowed to express his opinion before a jury.
U.S. District Court Judge Louise Wood Flanagan will rule on the issue before the trial, which is scheduled to begin next month.