20. In addition to the legal disqualifications and incapacities mentioned in section 16, any person who infringes the provisions of sections 16 to 20 commits an offence and is liable, on summary proceeding, in addition to the costs, to a fine of at least five hundred dollars and not more than one thousand dollars and, in default of payment of the fine and costs, to imprisonment for a term of at least three months and not more than six months.