I know a person who has taken ownership of a life ins policy without the original owners permission, is this legal? 
Absolutely not legal . The owner of the policy is the one with all the power to change the policy . In order for someone else to take control of the policy the owner would have to give their permission in writing . That form would be on file with the insurance company . If you feel the change was done in error or fraudulently you would need to have the original owner contact the insurance company . If they will not respond , which is possible , then a call to your state insurance complaint department will help . 