In the context of self defence we have a prima facie conflict of rights.
My right to bodily safety gives me a privilege to use reasonable force in
defending myself if you lunge at me with a carving knife. In striking the
balance between your right and mine, my belief that force is necessary
must be reasonable. It is not enough, as it would be in the criminal law,
that is is honestly held.

That the tort itself is, unquestionably, one of strict liability does not
conflict with this. If I kiss you, honestly and reasonably believing that
you consent when you do not, there is a battery. There is no conflict of
rights involved in such a case, and no question as to the scope of any
special privilege I may have by virtue of my own right to bodily safety.

In Vincent, prima facie, although completely blameless, the defendant’s
actions in intentionally tying up to the dock constituted a trespass as
they no longer had a licence after the withdrawal of consent by the dock
owner. Normally in such a case of intentional trespass the dock owner
would have the privilege to untie the boat’s cables, but this privilege
did not arise because of the emergency, so that if the cables had been
untied the dock owner would have been committing conversion, and
potentially liable for the full value of the ship if lost.  A judge at
dockside would not have restrained the boat’s owner from tying up, but the
privilege to do so was qualified, so that compensation was payable
calculated by reference to the loss suffered from the use. The defendant
was only within the privilege, and not committing a wrong, if compensation
representing the loss suffered was paid. The cause of action is not,
therefore, trespass, but there would be a trespass if the money for the
loss suffered was not paid. Here the defendant’s actions are justified not
merely excused.

Rob


> Along with Prosser, I disagree with the old cases and the Restatement
> position that a defendant who makes a reasonable mistake in self defense
> should not be liable for a battery.  I think those cases are poorly
> reasoned and were decided at a time when it was thought that to hold the
> defendant liable would label the defendant as being at fault and/or mean
> that the defendant should not have defended himself against the reasonably
> (but mistakenly) perceived attack.  Vincent has it right: this is SL, not
> fault.
>
> There of course was no mistake in Vincent, so the mistaken self-defense
> cases are inapposite.  The defendant there knew that he was trespassing on
> and damaging another's property without consent.
>
> The mistaken self-defense cases are an exception to the general position
> regarding mistaken trespass.  The results have been more mixed in cases
> involving mistaken defense of others.  As the Restatement indicates, the
> liability is clear in mistaken trespass to land or chattel cases and
> mistaken recapture of property cases, and also in cases involving mistaken
> belief that there is consent.
>
> ________________________________
>
> From: Stephen Sugarman [mailto:ssugarman@law.berkeley.edu]
> Sent: Tue 6/16/2009 5:48 PM
> To: Simon Douglas
> Cc: Wright, Richard; Tsachi Keren-Paz; obligations@uwo.ca
> Subject: Re: reasonable mistake and the reasonable person
>
>
>
> Where there is a battery claim and the defendant asserts self-defense but
> there was a reasonable mistake by the defendant (who thus injured an
> innocent party), the defendant wins according to the ALI Restatement and
> some old cases.
>
> See Section 63 Restatement of Torts (Second) (1965), especially comment h,
> illustration 7. The leading cases on this point are Courvoisier v.
> Raymond, 23 Colo. 113, 47 P. 284 (1896) and Crabtree v. Dawson, 119 Ky.
> 148, 83 S.W. 557 (1904). In the Reporter's Notes, Prosser wonders whether
> the defendant ought not bear the costs of his mistake.
>
> In my very long article on the "necessity" defense (in which I attack the
> VINCENT decision and the Restatement's endorsement of it), I use the
> rejection of "strict liability" by the Restatement and these cases for
> what could be termed trespass to the person as an example of how US law
> seems inconsistent.
>
> Steve Sugarman
>