What must happen before Vanessa's insurer will pay for the destruction of the borrowed pickup truck?

For the insurer to cover the destruction of the borrowed pickup truck, the owner's policy must pay first because of the principle of liability coverage. This approach stems from the fact that when you borrow a vehicle, the insurance of the vehicle's owner is typically responsible for covering any claims related to that vehicle. This includes damages or losses that occur while the vehicle is in your possession. Therefore, any claims will first be directed to the primary insurance policy — the owner's policy.

If the owner's insurance does not fully cover the damage or if there are specific coverage limits that apply, then Vanessa's own policy may kick in as secondary coverage, depending on the terms of her insurance. This establishes a clear order in the prioritization of claims and ensures the owner’s insurance acts as the primary defense.