In the CFL, if the game is tied at the end of regulation play, then each team is given an equal number of chances to break the tie. A coin toss is held to determine which team will take possession first; the first team scrimmages the ball at the opponent's 35-yard line and advances through a series of downs until it scores or loses possession. If the team scores a touchdown, starting with the 2010 season, it is required to attempt a 2-point conversion. The other team then scrimmages the ball at the same 35-yard line and has the same opportunity to score. After the teams have completed their possessions, if one team is ahead, then it is declared the winner; otherwise, the two teams each get another chance to score, scrimmaging from the other 35-yard line. After this second round, if there is still no winner, during the regular season the game ends as a tie. In a playoff or championship game, the teams continue to attempt to score from alternating 35-yard lines, until one team is leading after both have had an equal number of possessions.

What determines which team gets possession first when extending a game to break a tie?