Why can't Jim use his excess liability policy before exhausting his base policy's limit?

The reason Jim cannot use his excess liability policy before exhausting the limit of his base policy stems from the specific function of excess liability insurance. This type of policy is designed to provide additional coverage beyond the limits of an underlying base policy, meaning that it only pays out once the primary policy has reached its coverage limit.

In practical terms, the excess liability policy acts as a supplemental layer of protection against liability claims. It kicks in only after the limits of the base policy have been fully utilized. This requirement ensures that all parties involved in a claim first rely on the base coverage designed for straightforward liabilities, with the excess protection acting as a safety net for larger or more catastrophic claims that exceed those limits.

Therefore, Jim must exhaust the limit of his base policy before he can access the benefits provided by his excess liability policy, as that is the inherent nature and purpose of such an insurance arrangement.