British and US courts have ordered the provisional protection of Taisei Fire & Marine Insurance assets from creditors.
The Japanese non-life insurer failed last November because of huge payouts after the 11 September attacks on the US.
Taisei made use of a law that protects insurers filing for insolvency as the result of reinsurance claims stemming from terrorist attacks.
The order bars the company's creditors from individually filing lawsuits against it, Taisei said.
The company amassed Y74.4bn (£392m) losses after 11 September. Prior to its collapse, it was the sixteenth largest insurer in Japan, with premiums of Y88.7bn (£467m) in the year ended March 2001, and assets amounting to Y441.4bn (£2.3bn).
Japan's major property and casualty insurers are currently following the example set by the US and are considering reducing payouts to client companies in the event of a terrorist attack.
Insurers may exclude payments for large buildings, like skyscrapers and factories.
An insurance analyst said this could leave many buildings dangerously uninsured.