BeenThereDoneThat.
Summary of Pennsylvania Fishing Laws and Regulations ...fishandboat.com/.../equipment.h... 
Pennsylvania Fish and Boat Commission


RODS, LINES, AND HOOKS – An angler may use a maximum of three lines fished ...GAFF OR LANDING NET – A gaff or landing net is permitted to assist in ...

Never said it was illegal, but rather that nobody does it. 

outasync
I know several guys that carry and use gaffs

Wow.  Well, that's too bad, I guess Neanderthals have survived after all.

I'm not picking sides here but really, a gaff ! In the 60's & 70's yea.....but a net is just so much better all the way around for both. Sorry I'm not a fan of single hooks for Musky lures......barbless too ? I've lost enough without giving them more advantages.......10,000 casts is enough ! 

The 2 guys I know that do use them regularly only use them on fish they know they are going to keep. A few pike from conneaut lake or walleye from pymie or shenango. The only time I've ever used the gaf we have is to retrieve a dropped net lol

what is their reasoning for using a gaff?  do they lose a lot of 16'' walleye at the boat?  and are they worried about losing hammer handle pike?  

The proper use of a gaff is used on the lower jaw where a Boga would be used. Leaving a small hole. Used properly it is very efficient tool for releasing fish

Some people should heed their own advice. Say something useful please.  Nowhere was it stated that a gaff should be used on a hammer handle pike or 16 inch walleye. Nor would anyone i know say that it should be used on such fish. On a larger fish that you know you are going to keep (such as a 22 inch walleye or 30 inch pike, figured i had better put some numbers in to keep the peanut gallery happy) a well placed gaff put through the soft part of the lower jaw as anzo stated can be a very useful tool. The 2 guys i know that use them the most often both fish from pontoons and have on some occasions even put the gaff through the inside of the gills to lift the fish up into the boat.

im thinking like, the tuna fish show, harpoon and hit em w the gaff.  but still...  on a walleye or pike?  c'mon man.

Watch they don't put it through the pontoons. They do make great long handled nets in a variety of sizes.... I know I own about 10 different nets for fishing on boats and shore .....but I really don't need em !!! 
 

Ok..... OK for cryin out loud.  The gaff was brought about in comparison to using grips.  In either case, used wrong, they will undoubtedly injure or may lead to the death of a fish.  Not only are gaffs used to hook the fish in the fleshy part of the jaw, anglers will hook a fish under the gill plate or even impale the fish in other areas using the sharp point.  When grips are used, the fish will be taken by the jaw without any need for piercing the fish at all.  The fish may be taken from the water or (unlike the gaff) held in the water while hook(s) are [safely] removed.
 
For you "seasoned" anglers, fishing gaffs do come in various sizes and not just the long handled versions you see while watching your dream, deep sea fishing programs.
 
I tossed out the legality for the use of nets/gaffs in PA. for two reasons.  (1.) Gaffs were a popular landing device used by many anglers for years.  Since bigger nets, cradles and yes, the grips, have become available the gaff, once popular with (some) fresh water fisherman, is going by the wayside.  (2.)  If gaffs were not a popular landing tool and thought to be not needed, there would be no reason for such a law allowing for their use to begin with.  Therefore, they do exist and are still in use on PA.s waters, still today!
 
Really disappointing, was the missed opportunity to cry foul.............  there's no mention for the legal use of Boga Grips in the law.