http://t.thestar.com/#/article/sports/olympics/2012/08/11/london_2012_canada_disqualified_in_mens_4x100_relay.html says that Canada was on the podium...
until the judges saw that Connaughton, running the third leg and on the final turn, had taken one step on the lane line, earning the team an automatic disqualification.
I don't know what rule was violated. Can someone explain it?
Olympic track races are covered by the rules of the IAAF. You can download a PDF from the rules page. That PDF says, on page 159,
Lane Infringement
- (a) In all races run in lanes, each athlete shall keep within his allocated lane from start to finish. This shall also apply to any portion of a race run in lanes.
(b) In all races (or any part of races) not run in lanes, an athlete running on a bend, on the outer half of the track as per Rule 162.10, or on any curved part of the diversion from the track for the steeplechase water jump, shall not step or run on or inside the kerb or line marking the applicable border (the inside of the track, the outer half of the track, or any curved part of the diversion from the track for the steeplechase water jump).
Except as stated in Rule 163.4, if the Referee is satisfied, on the report of a Judge or Umpire or otherwise, that an athlete has violated this Rule, he shall be disqualified.
There is an exception if you're in a straight segment and gained no advantage, but the article says he was on the turn. The rule clearly says "shall not step or run on or inside the kerb or line" so stepping on the line breaks the rule.
