An Air Force judge on Sept. 23 dismissed charges against a former military training instructor accused of having an inappropriate relationship with one recruit and attempting a relationship with a second.

Tech. Sgt. Andrea Bell II was the second former MTI to head to court-martial this year for alleged sexual offenses involving trainees. But the special court-martial ended before it began when the judge tossed out the case, citing the prosecution's "failure to state a claim."

The legal term "means that, even assuming the prosecution proves every fact it alleged in the specification of the offense on the charge sheet, it does not violate any provision of the [Uniform Code of Military Justice,]" Geoffrey Corn, a South Texas College law professor and retired Army judge advocate general, said in an email. "In other words, they failed to properly allege a criminal act by the defendant. It is the military version of a motion to quash an indictment."

The ruling is exceedingly rare, Corn said.

Prosecutors may ask the judge for a reconsideration, said 502nd Air Base Wing spokeswoman Leslie Finstein. If the judge denies the request, the prosecution may appeal the ruling or bring charges against Bell at a later time. The Air Force did not immediately provide a charge sheet detailing the alleged offenses, including when they occurred.

Bell was the first MTI to head to court-martial since April for charges involving inappropriate conduct with trainees — and the 30th since the spring of 2012. Some of the crimes and alleged crimes occurred years ago but were uncovered as part of a comprehensive investigation into basic training following reports of rape, sexual assault and other forms of MTI sexual misconduct in the summer of 2011.

Air Education and Training Command, which oversees basic training, has said there have been no new such allegations in two years, indicating that the dozens of changes made to the organization in the aftermath of the scandal are working. Those include tougher restrictions on who can serve as an MTI, increased manning and a limit on how long an MTI can serve, plus new safeguards and reporting avenues for vulnerable recruits.

Of the 30 MTIs to be sent to court-martial, 27 were convicted on some or all of the charges brought by the Air Force. Those charges ranged from rape to inappropriate, but non-physical relationships. Only one MTI was acquitted. And Bell is just the second to have his charges dismissed at the outset.

A military judge in February 2013 threw out the case of Tech. Sgt. Samuel Wicks, ruling investigators had illegally searched his cell phone. Wicks' former girlfriend, also an MTI, had discovered what she believed were inappropriate messages between Wicks and former recruits. She took the phone after their breakup, reported what she'd seen and later gave the phone to authorities.

The prosecution appealed the judge's ruling, but the U.S. Court of Appeals for the Armed Forces sided with Wicks' defense, calling the evidence from the cell phone and all derivative evidence inadmissible.