When a party has waived the right to a jury trial by one of the acts or omissions listed in CCP 631, it may still seek relief from that waiver under CCP 631(g).  A trial court exercises discretion in ruling on such a motion and need not grant the motion merely because granting the motion will not cause hardship to other parties. While hardship is a primary consideration, the motion calls for consideration of other factors as well, such as the timeliness of the request and the reasons supporting it.  Also, on appeal from an order denying relief from a jury waiver, prejudice is not presumed but must be shown.  While denial of a jury trial when the right to a jury has not been waived is a structural error not requiring a showing of prejudice to obtain reversal, but not so for refusal to grant relief from a waiver of the right to a jury trial  Moreover, the preferred method for obtaining appellate review of denial of a jury trial is by a petition for writ of mandate–a pre-trial petition need not show prejudice and avoids the prospect of two trials.