Chapter 84:5
Laws of Carrying: Clothing & Jewelry
5. A lame person, a person who has just recovered from illness, and a very
old man - who are not able to walk without the aid of a cane - are allowed
to walk [in a public domain] carrying a cane [on Shabbos] (1). If,
however, the person is able to walk without a cane (2) and, although he
generally uses one for support when he goes out, he walks without using one
in his own house, he is forbidden to carry [the cane in the public domain
on Shabbos].
Similarly, a blind man may not carry a cane [on Shabbos] (3) in a city
which does not have an "Eiruv" (4). Furthermore, a person who doesn't need
a cane at all, is forbidden to walk out [into the public domain] with one,
even in a city that has an "Eiruv", for doing so demeans Shabbos ("Zilusa
DeShabbos").
FOOTNOTES:
(1) Since these people can't walk without the cane, it is considered
equivalent to their shoes, and not an extra burden that they are carrying
(Mishna Berura 301:63).
(2) This is true, even if the person's body trembles when he walks (MB 301:64).
(3) This is because a blind person only needs the cane for direction, but
not for the actual walking itself (MB 301:68). There are those who say that
it is only prohibited if the blind person knows his way around; however, if
he needs his cane in order to prevent tripping on things, he is likened to
the lame and may use his cane.
(4) An "eiruv" is an enclosure consisting of a series of poles or the like,
with wire or string pulled tight over the top of them. It turns the area
enclosed by it (sometimes even a number of neighborhoods), into a private
domain ("Reshus HaYochid"), thereby permitting carrying within it.
(5) Even if the cane is decorated beautifully, and one carries it as a
status symbol, it is still forbidden to carry it where there is no "eiruv."
This is because although it is considered equivalent to jewelry, one is
only permitted to wear jewelry, but not carry it in one's hands. However,
within an "eiruv," one may carry a cane as a status symbol or if there is
even a slight need for it. Only if there is no need whatsoever, is it
considered demeaning to Shabbos. (MB 301:66).