In determining premiums and premium rate structures, insurers consider quantifiable factors, including location, credit scores, gender, occupation, marital status, and education level. However, the use of such factors is often considered to be unfair or unlawfully discriminatory, and the reaction against this practice has in some instances led to political disputes about the ways in which insurers determine premiums and regulatory intervention to limit the factors used.

An insurance underwriter's job is to evaluate a given risk as to the likelihood that a loss will occur. Any factor that causes a greater likelihood of loss should theoretically be charged a higher rate. This basic principle of insurance must be followed if insurance companies are to remain solvent. Thus, "discrimination" against (i.e., differential treatment of) potential insureds in the risk evaluation and premium-setting process is a necessary by-product of the fundamentals of insurance underwriting. For instance, insurers charge older people significantly higher premiums than they charge younger people for term life insurance. Older people are thus treated differently than younger people (i.e., a distinction is made, discrimination occurs). The rationale for the differential treatment goes to the heart of the risk a life insurer takes: Old people are likely to die sooner than young people, so the risk of loss (the insured's death) is greater in any given period of time and therefore the risk premium must be higher to cover the greater risk. However, treating insureds differently when there is no actuarially sound reason for doing so is unlawful discrimination.

What is often missing from the debate is that prohibiting the use of legitimate, actuarially sound factors means that an insufficient amount is being charged for a given risk, and there is thus a deficit in the system. The failure to address the deficit may mean insolvency and hardship for all of a company's insureds. The options for addressing the deficit seem to be the following: Charge the deficit to the other policyholders or charge it to the government (i.e., externalize outside of the company to society at large).

Reference: www.wikipedia.org