Major League Baseball is using expanded instant replay for the first time this season. The new system allows managers to ask for a replay. The wikipedia entry on MLB instant replay explains it well:
(M)anagers will be allotted one challenge per game (two if the first challenge results in an overturned call) while the umpiring crew chief will be empowered to initiate a review in innings 7 and later. The umpires will also be allowed to review a home run call at any time, even during innings #1-6. Once a call is challenged an umpire requests a video review, fellow umpires in New York’s Replay Command Center will watch video of the play in question using the “indisputable video evidence” standard when deciding whether to overturn a call.
As with anything MLB does, the system has critics, but I like the replay system. It’s almost perfect.
The only thing I would change is the manager challenge part. That just seems hokey.
If the objective is to get the call right, then either team or any umpire should be able to ask for a replay on any play at any time, regardless of what inning it is or if a manager has “challenges” left. (I feel the same way about the use of replay in football, too.)