where a number of insurance companies are liable under one policy, the principle applicable is ?

The principle applicable where a number of insurance companies are liable under one policy is "contribution". Contribution means that each insurer is liable to contribute a proportionate amount to the loss covered by the policy. This applies in cases where multiple insurers have provided coverage for the same risk, and ensures that the insured is fully compensated for the loss without any one insurer having to bear the entire burden. The amount each insurer is required to contribute is generally determined by the terms of the policy, and is proportional to the amount of coverage each has provided.