BALTIMORE (AP/MEDIA GENERAL) – One of the Baltimore police officers who arrested Freddie Gray has challenged police and a top prosecutor to produce a knife that prompted the arrest, arguing in a court motion that it is an illegal weapon.

Attorneys filed the motion in Baltimore District Court for Officer Edward Nero, who is charged with second-degree assault, misconduct in office and false imprisonment. The motion appeared to challenge the basis for charges Nero faces after the arrest of Gray, a black man who died a week after suffering a severe spinal injury in police custody.The Law

According to the Baltimore Sun, there are very small differences in the descriptions the state of Maryland and the city of Baltimore use to classify which knives are illegal.

The Baltimore Sun reports “state law says a person may not ‘display’ a ‘switchblade’ or a ‘knife or a penknife having a blade that opens automatically by hand pressure applied to a button, spring, or other device in the handle of the knife.’”

“Baltimore City code says a person can’t carry or possess any knife ‘with an automatic spring or other device for opening and/or closing the blade, commonly known as a switch-blade knife.’”The Knife:

Some spring-assisted knives are opened by pushing a thumb stud attached to the blade.

Many knives have these spring-assisted opening mechanisms but are not the automatic knives prohibited under Maryland law, said Michael Faith, marketing director for Henderson’s Sporting Goods in Hagerstown.

“An automatic knife means all you do is push a button and the blade pops out,” Faith said. “A lot of knives will have a little spring assist so when you push it open with your thumb, the knife will open up pretty much by itself.”

The Baltimore Sun reports that a Baltimore police task force, commissioned to investigate Gray’s death, reviewed the knife and reported it was “spring assisted” and violated city law.

Last Friday, Baltimore City State’s Attorney Marilyn Mosby said the officers had unlawfully arrested Gray because the knife he had in his pocket is considered legal under Maryland state law.

Marc Zayon, Edward Nero’s attorney, argued in the motion that the knife in Gray’s pocket – described in charging documents as “a spring assisted, one hand operated knife” – is in fact illegal under state law. Maryland, he said, defines a knife as unlawful if it opens automatically by pushing a button, spring or other device in the handle.Does the Knife Matter?

Police said officers chased Gray two blocks after making eye contact with him and subsequently found the knife in his pocket. Mosby along with demonstrators have said police did not have probable cause to stop Gray in the first place. Only when officers stopped Gray, did they find the knife and make the arrest.

Some lawyers including Andy Alperstein, who has represented police officers but is not involved in the Gray case, said the charges of false imprisonment can only be proven if Gray was wrongly arrested. If the knife was illegal, “there is no case” against Nero and another officer, he said.

“If the facts were that the knife was illegal then the Gray arrest would be justified. Even if it wasn’t illegal and the officers acted in good faith, it would be the same result. All charges fail,” Alperstein said.

The Associated Press has made repeated requests to the police department for a physical description of the knife as well as photographs. Police later referred the request to the state’s attorney’s office.

Nero and Officer Garrett Miller are charged with misdemeanors. Four others – Sgt. Alicia White, Lt. Brian Rice and officers Caesar Goodson and William Porter – are charged with felonies ranging from manslaughter to second-degree “depraved-heart” murder.

Calls to attorneys representing Miller and Rice, who were involved in Gray’s arrest, were not immediately returned.

Mosby’s office declined to comment on a pending case, citing prosecutorial ethics.