With each sentence that is handed down, prosecutors and judges are trying to send a message to deter crime.

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Mr Duggan reasoned that for guns to deter crime, the passage of concealed-weapons laws must either lead to more gun ownership or to more frequent carrying of previously owned weapons.

ECONOMIST: Economics focus

Ms Lo referred to earlier schemes to deter the crime of "joyriding" and said there was a need to be "proactive" in bringing young disenfranchised people back into society.

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The theory is that exposure to the grim realities of life in prison will deter at-risk youths from future crime.

ECONOMIST: Social science

By publicising the government's efforts to fight crime, they help to deter it, as well as strengthening public confidence in the police.

ECONOMIST: Law and the media

As well as tackling violent crime, the troops will support police and community groups to deter offences such as street drug-dealing and public drunkenness.

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