"Bear spray" long has been recommended by national parks in the West as a great deterrent against grizzly and black bears. Indeed, among those parks endorsing bear spray are Yellowstone National Park, Glacier National Park, and Grand Teton National Park.
Here's a snippet from a transcript to a video Yellowstone's staff (see accompanying videocast) produced on bear spray:
When bear encounters do occur, one response has been effective in consistently reducing the number of bear attacks with severe outcomes, the use of bear pepper spray. More and more people carry bear pepper spray in the field, professionals, outfitters, and everyday hikers and campers. Many can testify to the effectiveness of bear pepper spray as a bear deterrent, from bear specialists to outfitters, guides, and hunters.
At Glacier, officials also recommend bear spray, although they stress that you shouldn't gain a false sense of security by carrying a can or two.
This aerosol pepper derivative triggers temporarily incapacitating discomfort in bears. It is a non-toxic and non-lethal means of deterring bears.
There have been cases where bear spray apparently repelled aggressive or attacking bears and accounts where it has not worked as well as expected. Factors influencing effectiveness include distance, wind, rainy weather, temperature extremes, and product shelf life.
If you decide to carry bear spray, use it only in situations where aggressive bear behavior justifies its use. Bear spray is intended to be sprayed into the face of an oncoming bear. It is not intended to act as a repellent.
While this is all good advice, a check of the Code of Federal Regulations (Title 36, Chapter 1, see 'weapons' definition) shows those parks seem to be overlooking a prohibition against bear spray in national parks because it can be considered a weapon.
Weapon means a firearm, compressed gas or spring-powered pistol or rifle, bow and arrow, crossbow, blowgun, speargun, hand-thrown spear, slingshot, irritant gas device, explosive device, or any other implement designed to discharge missiles, and includes a weapon the possession of which is prohibited under the laws of the State in which the park area or portion thereof is located. (emphasis added)
Park Service officials in Washington tell the Traveler that the regulations do indeed seem to prohibit bear spray in many national parks. And they point out that while there is language that specifically allows the use of bear spray in Alaskan parks elsewhere in the Code of Federal Regulations, "(T)here is not a provision for it in the Lower 48 for some reason."
Thanks to Christoper Hibbard at Your Smokies for bringing this issue to the Traveler's attention.