When I read the CBA, it seems to allow the NHL to consider all prior supplementary discipline (and doesn't matter if it was in the last 18 months) as well as all violations of league rules (not just those that received supplementary discipline). It seems to give more weight to prior suspensions (or fines) but it doesn't seem to limit it to those infractions. And the only place I can find a time limit (18 months) is in the rules concerning fines (18.7(e)) and forfeiture of compensation (18.15), so it seems irrelevant when it comes to deciding a suspension's length (except that prior fines that season must be considered in determining the length of a suspension).
Here's the relevant passage:
18.2 General. It is the parties' intention to impose Supplementary Discipline for On-Ice
Conduct in a swift, effective and consistent manner with respect to conduct proscribed by
League Playing Rules, including the use of excessive and unnecessary force and reckless acts
resulting in injury. In doing so, however, the parties do not intend to alter the basic fabric of our
game. In deciding on Supplementary Discipline for On-Ice Conduct, the following factors will
be taken into account:
(a) The type of conduct involved: conduct in violation of League Playing Rules, and
whether the conduct is intentional or reckless, and involves the use of excessive and unnecessary
force. Players are responsible for the consequences of their actions.
(b) Injury to the opposing Player(s) involved in the incident.
(c) The status of the offender and, specifically, whether the Player has a history of
being subject to Supplementary Discipline for On-Ice Conduct. Players who repeatedly violate
League Playing Rules will be more severely punished for each new violation.
(d) The situation of the game in which the incident occurred, for example: late in the
game, lopsided score, prior events in the game.
(e) Such other factors as may be appropriate in the circumstances.
I believe that the bolded part is a change from the prior CBA.
I'm not sure I'm interpreting the CBA correctly but I hope I am. I hope that they can consider all Lapierre's past hits. Does anyone here know?