1. A method for coding video data, the method comprising: determining whether a prediction unit (PU) in a B slice is restricted to uni-directional inter prediction; generating a merge candidate list for the PU; determining a selected merge candidate in the merge candidate list; if the PU is restricted to uni-directional inter prediction, generating a predictive video block for the PU based on no more than one reference block associated with motion information specified by the selected merge candidate; and if the PU is not restricted to uni-directional inter prediction, generating the predictive video block for the PU based on one or more reference blocks associated with the motion information specified by the selected merge candidate.