In Pennsylvania, you can carry a weapon for defensive purposes, but you cannot carry every type of defensive weapon even if your intent in carrying it is solely for defensive purposes. Also, if some is injured as a result of your actions, you could be prosecuted not just for the weapon, but also for assault.
Some weapons in Pennsylvania are called Prohibited Offensive Weapons, and if the weapon you possess meets any of the definitions below, you cannot carry the weapon even for defensive purposes. Further, note in the definitional section below the of the actual offensive weapons, that a blackjack and a spring loaded weapon are both mentioned. Many defensive weapons fit a combination of these two and are therefore not allow.
The following picture is an example of a spring loaded baton, and the statute follows.
Spring Loaded Baton
A POW is defined below:
§ 908. Prohibited offensive weapons
(a) OFFENSE DEFINED.– A person commits a misdemeanor of the first degree if, except as authorized by law, he makes repairs, sells, or otherwise deals in, uses, or possesses any offensive weapon.
(b) EXCEPTIONS.–
(1) It is a defense under this section for the defendant to prove by a
preponderance of evidence that he possessed or dealt with the weapon
solely as a curio or in a dramatic performance, or that, with the
exception of a bomb, grenade or incendiary device, he complied with the
National Firearms Act (26 U.S.C. § 5801 et seq.), or that he possessed
it briefly in consequence of having found it or taken it from an
aggressor, or under circumstances similarly negativing any intent or
likelihood that the weapon would be used unlawfully.
(2) This section does not apply to police forensic firearms experts or
police forensic firearms laboratories. Also exempt from this section
are forensic firearms experts or forensic firearms laboratories
operating in the ordinary course of business and engaged in lawful
operation who notify in writing, on an annual basis, the chief or head
of any police force or police department of a city, and, elsewhere, the
sheriff of a county in which they are located, of the possession, type
and use of offensive weapons.
(3) This section shall not apply to any person who makes, repairs,
sells or otherwise deals in, uses or possesses any firearm for purposes
not prohibited by the laws of this Commonwealth.
(c) DEFINITIONS.– As used in this section, the following words and phrases shall have the meanings given to them in this subsection:
“Firearm.” Any weapon which is designed to or may readily be converted to expel any projectile by the action of an explosive or the frame or receiver of any such weapon.
“Offensive weapons.” Any bomb, grenade, machine gun, sawed-off shotgun with a barrel less than 18 inches, firearm specially made or specially adapted for concealment or silent discharge, any blackjack, sandbag, metal knuckles, dagger, knife, razor or cutting instrument, the blade of which is exposed in an automatic way by switch, push-button, spring mechanism, or otherwise, any stun gun, stun baton, taser or other electronic or electric weapon or other implement for the infliction of serious bodily injury which serves no common lawful purpose.
(d) EXEMPTIONS.– The use and possession of blackjacks by the following persons in the course of their duties are exempt from this section:
(1) Police officers, as defined by and who meet the requirements of the
act of June 18, 1974 (P.L. 359, No. 120), referred to as the Municipal
Police Education and Training Law.
(2) Police officers of first class cities who have successfully
completed training which is substantially equivalent to the program
under the Municipal Police Education and Training Law.
(3) Pennsylvania State Police officers.
(4) Sheriffs and deputy sheriffs of the various counties who have
satisfactorily met the requirements of the Municipal Police Education
and Training Law.
(5) Police officers employed by the Commonwealth who have
satisfactorily met the requirements of the Municipal Police Education
and Training Law.
(6) Deputy sheriffs with adequate training as determined by the
Pennsylvania Commission on Crime and Delinquency.
(7) Liquor Control Board agents who have satisfactorily met the
requirements of the Municipal Police Education and Training Law.
