Obviously professional criminals aren't going to be put off having guns by laws, and there are ways of getting hold of them. But gun controls make it that bit harder - they can ensure that there aren't as many around to get stolen, for example, and those that are around are less easily accessible.

And some of the most terrible gun murders, such as the Amish school massacre in Pennsylvania this week, or Dunblane, have been carried oput by people who were not professional criminals, and who used guns that had been obtained legally.