In the end, Freddie Gray paid the ultimate price for the crime of clipping a common knife to his pocket.

After Mr. Gray ran from police seconds after “making eye contact,” officers quickly grabbed the 20-something black Baltimore man and arrested him for carrying what they called a concealed deadly weapon banned by Maryland – what turned out to be a short-bladed folding-knife similar to ones worn everyday by millions of law-abiding Americans.

A week later, Gray was dead from injuries received while in police custody. The Justice Department opened a civil rights investigation into his death, and the mayor of Baltimore was publicly questioning whether anything Gray did or wore should really have been a precursor to arrest. Large protests have erupted in Baltimore after a coroner found that Gray’s vertebrae were broken while he was in custody, and that he was refused immediate medical care for injuries that eventually became fatal. Six officers have been suspended with pay.

For their part, police say Gray, who had a minor criminal record, "fled unprovoked upon noticing police presence." Then, "the officer noticed a knife clipped to the inside of (Gray's) front right pants pocket. The knife was recovered by this officer and found to be a spring assisted, one-hand-operated knife."

The uproar over Gray’s mysterious death and the circumstances of his arrest comes amid a seismic shift in knife rights, as growing numbers of states are lifting knife bans. The issue also resonates as the country debates the essential fairness of the US justice system, where critics say obscure laws like knife bans have at times been used selectively by police and prosecutors to clean up poor minority neighborhoods under zero-tolerance and "broken windows" style policing.

The immediate question for investigators is whether that knife qualifies as a “switchblade” under Baltimore city statutes, given that Gray’s specimen was not a fully automatic knife. Another is whether, if officers spotted the knife without searching Gray, it could really be considered concealed. Outside of Baltimore, almost any knife can be worn in the state as long as it can be seen by others.

But given court rulings and crime statistics that show that such knives are primarily used as tools, not weapons, a larger question emerging for legislators in states like Maryland is whether bans on certain kinds of concealed knives can too easily become convenient excuses for police officers to achieve arrests in minority neighborhoods, thus dovetailing into national concerns about police stereotyping and conduct.

“Too often we see an officer who may or may not understand the law arrest somebody for having an illegal knife that isn’t illegal,” says Doug Ritter, founder of the Arizona-based Knife Rights group. “We too often see that kind of either blatant ignorance of the law or willful ignorance of the law, in an effort to abuse citizens' rights to carry this tool.”

Reconsideration of knife bans began as early as the 1980s, when the Oregon Supreme Court found that “[i]t is not the design of the knife but the use to which it is put that determines its ‘offensive’ or ‘defensive’ character.” A failed 2009 attempt by the US Customs Service to establish an import ban on tactical knives stirred knife rights activists to action, given that the rule could have impacted nearly 80 percent of knives in the US. Since then, activists have helped pass 13 pro-knife bills in 11 states.

To be sure, Americans have long feared and banned blades, starting with a public backlash against Bowie and Arkansas toothpick knives in the mid-1800s. More recently, in Manhattan, District Attorney Cyrus Vance took on major retailers for sales of certain kinds of spring or gravity-assisted knives, and police have arrested roofers, artists, and fishermen for violating local knife bans, based on the view, in the words of one court ruling, that only “ruffians” carry certain kinds of knives.

Opening knives like the switchblade “is visually interesting and frightening to some persons unfamiliar with knives, creating a belief that it is an extremely dangerous weapon necessitating special legislative attention,” explains Dave Kopel, research director at the Independence Institute in Denver, in a University of Michigan Journal of Law Reform article.

Some police say concealed carry of knives is dangerous and should be banned. “Any double-edged knife that can penetrate a bulletproof vest seems like a weapon made to kill,” Chuck Callaway, a lobbyist for the Las Vegas Metropolitan Police Department, told the Los Angeles Times in response to a knife decriminalization bill in Nevada. “Why would we legalize them to be carried concealed?”

Some 60,000 knife owners in New York City alone have been arrested carrying certain kinds of knives, including gravity-assisted folding blades, on their persons. A proposed new law would make it illegal only to use such knives in the commission of a crime.

Since 2010, seven states have ordered that municipalities, like Baltimore, can’t enact knife laws that are stronger than the state law. Many lawmakers are unaware that cities are allowed to write more stringent knife rules than state law, activists say. A total of 38 states allow switchblades, 26 of those with no restrictions on blade length or concealed-carry. The federal government, however, under the Switchblade Act of 1958, still bars the interstate commerce of such knives. Historians say the act was passed largely because of societal fears of knife-wielding gangs whipped up by Hollywood.

But in modern America, the fact that a common roofer’s tool is seen by some state lawmakers and police as a deadly weapon if worn in the inner city ties into the nation’s racial history, argues Mr. Ritter, especially given that the first knife bans were aimed at emancipated blacks in Southern states who could afford no other self-defense weaponry.

Alarm over knife dangers, the Oregon Supreme Court noted in 1984, clashes with the actual history of knives in America. “It is clear … that knives have played an important role in American life, both as tools and as weapons,” the court wrote in State v. Delgado. “The folding pocketknife, in particular, since the early 18th century has been commonly carried by men in America and used primarily for work, but also for fighting.”

Today, knives are used less than “other weapons” for committing robbery and aggravated assault, according to the FBI; 13 percent of US murders are committed with a knife or “cutting instruments,” compared with 68 percent of homicides being committed with a gun.

In 2007, a federal court in New York questioned the decision by police to ascertain that certain knife-carriers are criminals. The court in US v. Irizarry found that “the widespread and lawful presence of an item in society undercuts the reasonableness of an officer’s belief that it represents contraband.”

While primarily conservative states have eased knife restrictions in recent years, the movement is largely bipartisan, says Ritter.

In Texas, for example, Harold Dutton, a Democratic state legislator with an F rating from the National Rifle Association, championed an effort to make switchblades legal, on the grounds that police used the knife ban disproportionately to arrest black men.