What is the role of a trial court in granting a motion for a new trial?

Our observations in People v. Andrade (2000) 79 Cal.App.4th 651, 661, are equally apposite in the civil context: "A trial court serves as a 'gatekeeper' on a motion for new trial. It opens the gate only rarely, a testament to the fact that the vast majority of trials... are fairly conducted. In these cases, motions for new trial are routinely made, routinely denied, and are routinely affirmed on appeal. In the remaining cases, however, the trial court grants the motion, and we affirm those rulings in the absence of a clear showing of abuse of discretion. [Citation.]"