The Copenhagen Post reports:

A 17-year-old girl in Sønderborg has found herself in violation of the arms act for using pepper spray on an English-speaking man who tried to pull down her trousers.
The girl notified police in southern Jutland police that she had been sexually assaulted across the street from the Sønderborg cultural and community centre ….

The Telegraph (U.K.) discuss the story as well:

Local police spokesman Knud Kirsten told TV Syd: ‘It is illegal to possess and use pepper spray, so she will likely to be charged for that.’

Last week, the Copenhagen Post reported that “An increasing number of Danes are travelling to Germany to buy pepper spray.”

At least as of 2009, irritant sprays — and also stun guns — were also largely banned in England, Canada, New Zealand, and much of Australia (see p. 213 of this article), and I have heard the same about other European countries. (My understanding is that Denmark requires a license to possess stun guns, but I don’t know whether such a license is generally available. [UPDATE: The Danish Justice Ministry informs me that “under Danish Legislation it is illegal to buy, possess, carry or use electrical shock weapons, such as tasers, unless you have obtained a license from the Danish Police. The Danish Police only issues such licenses as an exception, and if the particular case presents exceptional circumstances."]) Those countries thus deny people the ability to defend themselves not just with guns but also with (almost entirely) nonlethal weapons.

Some American jurisdictions used to ban pepper sprays, and several still ban stun guns. (The Supreme Court is considering whether to hear a case about one of the remaining stun gun bans; see this post, which quotes a friend-of-the-court brief I filed in that case on behalf of Arming Women Against Rape & Endangerment.) And more jurisdictions ban pepper spray and stun gun possession by under-18-year-olds; for why I think that’s unconstitutional in the United States as to older minors, see this article.

Note also what I call the anticooperative effect of law. Some people might react to this by not carrying pepper spray. But if a woman is carrying the pepper spray illegally and successfully fends off an attacker — or unsuccessfully tries to do so — will she go to the police so the attacker can be caught and his next attack prevented? Or will she keep quiet, since she doesn’t want to be prosecuted herself? (Note that pepper spray possession is apparently just punishable by a fine: not likely to greatly deter people from carrying, but likely enough to deter many pepper spray users from going to the police.)