This article is from the PGP FAQ, by Jeff Licquia email@example.com with numerous contributions by others.
It's still too early to tell. At least one company is using PGP
digital signatures on contracts to provide "quick agreement" via
E-mail, allowing work to proceed without having to wait for the paper
signature. Two USA states (Utah and Wyoming) have passed laws
recently giving digital signatures binding force for certain kinds of
transactions. The Wyoming law is available from:
This non-lawyerly mind sees two questions which need to be considered.
First, a "signature" is nothing more than an agreement to a contract;
verbal "signatures" have been upheld before in court. It would seem
that, if such a dispute were to arise, that a valid digital signature
could be seen as evidence that such an agreement was made. Second,
PGP keys are much easier to compromise than a person's handwritten
signature, so their evidential value will by necessity be less.