The Federal Bureau of Investigation has some explaining to do this week, after a federal judge ordered the agency to provide a more thorough explanation to justify why it withheld information from a graduate student’s Freedom of Information Act request for documents regarding an alleged 2011 assassination plot against leaders of Houston’s Occupy movement.

The requests — which were filed last year by Massachusetts Institute of Technology doctoral candidate Ryan Noah Shapiro, who is researching the plot — sought all records “relating or referring to Occupy Houston, any other Occupy Wall Street-related protests in Houston, Texas, and law enforcement responses.” Shapiro noticed a reference to the plot in FBI documents about the Occupy movement that were unsealed in 2012 after a civil-rights group filed a FOIA request.

An FBI document that Shapiro showed to VICE News describes the plot against Occupy Houston:

“An identified [redacted] as of October planned to engage in sniper attacks against protestors [sic] in Houston, Texas, if deemed necessary…. [Redacted] planned to gather intelligence against the leaders of the protest groups and obtain photographs, then formulate a plan to kill the leadership via suppressed sniper rifles.”

The FBI said it had identified 17 pages of records relevant to Shapiro’s FOIA request, but it only released five of them, all highly redacted. Shapiro then filed suit against the FBI.

FBI FOIA Chief David Hardy defended suppressing the information in a motion to dismiss Shapiro’s lawsuit. Hardy noted that the request concerned material that the FBI had given to local authorities who were investigating “potential criminal activity” by Occupy Houston protesters. The FBI was working with them to assess potential terrorist threats posed by Occupy Houston and determine whether it had advocated overthrowing the US government. Hardy .

The FBI and the Department of Justice invoked the Bureau’s “general investigative authority” and its “lead role in investigating terrorism and in the collection of terrorism threat information” as a basis for its exemption from FOIA, but this did not convince Judge Rosemary M. Collyer of the US District Court for the District of Columbia. She agreed with Shapiro that the FBI’s justification was “overly-generalized and not particular.”

“At no point does Mr. Hardy supply specific facts as to the basis for the FBI’s belief that the Occupy protestors [sic] might have been engaged in terroristic or other criminal activity,” Collyer wrote in an opinion that denied part of the FBI's motion to dismiss. “Neither the word ‘terrorism’ nor the phrase ‘advocating the overthrow of the government’ are talismanic, especially where FBI purports to be investigating individuals who ostensibly are engaged in protected First Amendment activity.”

VICE News asked the Department of Justice for its reaction to Judge Collyer’s opinion, but it declined to comment.

Shapiro, who currently has more than 700 active FOIA requests and four other pending lawsuits with the FBI, told VICE News that he’s not surprised that the FBI is stonewalling.

“The FBI is again hiding behind vague unsupported allegations of ‘terrorism’ and threats to national security to withhold these documents,” he said. “Not only is this far-fetched, it highlights that we as a nation need to foster a broader understanding of ‘national security.’ ”

Shapiro is doubtful that the FBI has truthfully acknowledged the records relevant to his requests, and wonders whether the Bureau investigated the plot to assassinate US citizens on domestic soil for exercising their First Amendment rights.

“Here we have an FBI investigation of purported possible terrorism and attempts to overthrow the American government by a protest group, and the discovery during this investigation of an actual terrorist plot to assassinate the leaders of that protest group,” he said. “And yet, the FBI is claiming it amassed only 17 pages total on all of the above? Well, beyond implausible, the FBI’s claim is preposterous.”

Jeffrey Light, Shapiro’s attorney, told VICE News that the FBI’s standing as a law enforcement agency only goes so far.

“Just because you are a law enforcement agency, by definition, doesn’t mean that everything that you do is for law enforcement purposes,” he explained. “You could be, for example, monitoring political activists. That’s not a law enforcement purpose. The argument is that there’s not enough information.”

Collyer has given the FBI until April 9th to provide a more detailed explanation for its exemptions, which the Bureau can submit to the court under seal.

Follow Maxwell Barna on Twitter: @Maxwell_BarnaNJ