Linda and Morris Tannehill believe that big businesses will tend to pay the bulk of the defense costs (since they stand to lose the most in the event of an attack); they would then pass on the costs to their customers, and so the costs of defense would be spread out among the whole population. A landowner seeking to establish a community may sell or lease the land with provisions written into the deed or lease agreement, requiring the new owner or tenant to pay for defense on a permanent basis; this same technique has already been in some neighborhoods to ensure that residents pay for private streets shared in common by all of them. As is true for homeowners today, everyone would be responsible for buying or otherwise being covered by aggression insurance in order to protect themselves against catastrophic loss from foreign attack; in the event of an invasion, a claim would be filed with right of subrogation, and the insurer would hire a private defense company to collect from the aggressor. An argument against this method of funding is that other aggression insurers who didn't pay for defense would still benefit from the reduced risk of attack on their customers in the same area, in effect becoming free riders who could drive the "altruistic" insurer out of business. However, the private defense agency's activity need not be limited to defensive and retaliatory measures funded by the insurer; It could also go after the aggressor in an effort to obtain restitution (including reasonable collection costs), perhaps through ransom or capture of enemy assets, as privateers did in the 18th and 19th centuries under letters of marque and reprisal. Prisoners of war also used to have shadow prices (ransoms) which were a source of income for victorious forces; this represents another potential alternative to taxation.