Most norms which allow for enforced restitution, defensive, or retributive action operate on a basis of a truce of mutually beneficial relationships. This includes norms for property and non-aggression.
Property primarily describes who may access or control something, and the permissible and impermissible actions of other persons. So long as persons respect these norms, they are considered in good-status or protected-status, and any violation of the truce by another against them is considered an act of "injustice" - or a breach of truce.
Once the truce is breached, it is generally considered a non-breach to engage in activity against the person who breached the truce in proportion to the severity of violation. Depending on available systems, this may involve defense, retribution, arbitration, or some form of enforcement. This is especially applicable for norms regarding dispute prevention and resolution.
Even under "non propertarian," standards of the truce might include "outlawing" hoarding and preventing access, and treat those as a violation of truce. While in more propertarian systems of interaction, these norms would be imbalanced, in a non-propertarian system refusing access may be a breach of truce/balance in the sense "You use my/our means of resources, but do not allow me to use yours."
One may also consider the interaction between divergent systems, and how a singular truce may not be automatically applied to all persons. If a propertarian-anarchist (who doesn't share resources) visits a mutualist-cooperative, they may be denied access to the mutualist' resources unless or until they acquire consent or contribute similarly in return.
Not every relationship must be identical. Within the mutualist community, they have one standard for their mutually-beneficial relationships including shared ownership and access. Between the mutualist cooperative and an outside individual, they have another standard of barter and trade.
- "Mutually Beneficial Truce" theory does not pretend to offer an objective metric of the morality of any given system of norms.