The last post was very long, so this one will be short! There's a theory that to the extent that landowners are liable in tort for preventing crime on their property, they are essentially called upon to perform the functions usually associated with public law enforcement. Law Professor Barbara Glesner Fines wrote an influential law review article in 1992 making this case: Landlords as Cops: Tort, Nuisance & Forfeiture Standards Imposing Liability on Landlords for Crime on the Premises, 42 Case Western Reserve Law Review 679, 773 (1992) (available on Westlaw):
From a societal perspective, shifting responsibility for crime prevention to landlords is neither efficient nor effective . . . . [T]here is a danger of encouraging the "deputization" of the citizenry. Moreover, criminal law enforcement efforts become more hidden, thereby increasing the corresponding opportunity for corruption and discriminatory enforcement and inviting the practice of unrestrained vigilantism.
It is interesting to think about whether this is still a persuasive argument, when highly publicized incidences of prosecutorial misconduct and discriminatory enforcement diminish public regard for government law enforcement efforts and, at the same time, dangers presented by the War on Terror encourage private citizens to be watchful and respond to perceived threats to our safety (e.g., when civilian airline passengers restrain a fellow passenger who is perceived to be a threat).