I know a person who has taken ownership of a life ins policy without the original owners permission, is this legal? 
There could be confusion about ownership . The owner of the policy can be someone other than the insured . For a variety of reasons the owner of the policy could be a former spouse for example . An insurance company must respond to the owner of the policy , unless the owner is deemed incompetent . In the case of incompetency , the court appoints a conservator . The conservator acts on behalf of the owner of the policy but must the actions of the conservator are under the scrutiny of the court . 