Erika Morphy is co-editor of Debt and Equity Journal, from which this article is excerpted.

Washington, DC—Commercial property insurance policyholders are generally satisfied with proposed House legislation expanding the federal program to assist the insurance industry in the event of a major terrorist attack. In a vote late last month, the House approved the Terrorism Risk Insurance Revision and Extension Act of 2007, which extends the terrorism risk insurance program for 15 years. It also adds group life insurance, broadens the federal backstop to include domestic terrorism as well as support for damages caused by nuclear, biological, chemical or radiological attacks and adjusts the damage levels triggering coverage under the act.

However, if these additional measures actually become law, there could be dramatic increases in insurance premiums for conventional terrorism attacks. Worse, some industry experts say, if insurance against perils like nuclear attacks becomes available on the private market, lenders will likely insist on such coverage in their underwriting--and there are concerns such coverage could be prohibitively expensive.

"I think the law of unintended consequences will kick in," says Aaron Davis, director of national property brokerage at Aon Corp., "because this type of coverage won't be subject to pricing controls. In addition, we think its inclusion could also be problematic because it could affect conventional terrorism pricing and capacity, making the latter more expensive and scarce." While nuclear, biological and chemical threats are real and something for which the insurance and real estate industries must prepare, the immediate risks are conventional attacks, he says.