Infraction system is is part of forum's core software. Nobody used it here at past, but it is here since forum moved to new platform 2 winters ago.
At past moderators/owner watched forum and made ban/suspension after wrong behavior of member. I think it is not that flexible - wait, wait, and then use "banhammer". So we started to use infraction system - each wrong behavior will "cost" to member some infraction points. Given infractions will be "burned" with time (usually after 30-60-90 days - depends on rule what has been breached).
Robot watches forum nonstop and calculating infraction points for each member. If total sum of "not burned with time points" will be 15 or more points - robot will suspend member for one week. If member will continue his wrong behavior and will receive more infractions and total sum will be 25 or more points - then member will receive 1 month of suspension. Last level - 35 points. At this level member will receive 3 months of suspension.
It works like driving licenses in many countries - if you have too many infractions on the roads, you may lose your driving license for some period of time first and forever after.