The NHL enacted a rule change that assesses an additional two-minute minor for unsportsmanlike conduct to any player who removes his helmet before a fight.
Krys Barch and Brett Gallant found a loophole to this rule when the two players unstrapped their helmets and removed the other player's helmet instead of their own. The players were only assessed five-minute fighting majors during the exchange.
Apparently, the loophole has already been closed.
Aaron Volpatti of the Washington Capitals and Kevan Miller of the Boston Bruins attempted to exploit the same tactic before their fight on Monday night. The two players didn't actually achieve the helmet exchange, as Volpatti removed both helmets simultaneously, but regardless, each player was given an extra two-minute minor on top of their fighting major.
The NHL wants players to keep their helmets on during fights so that they aren't susceptible to head injury from their heads hitting the ice. While the decision to enact this rule might be controversial, it's sensible that the league would enforce the unsportsmanlike conduct penalty in the future when helmets are intentionally removed in the fashion that Barch and Gallant did.