Here’s a case from New Jersey of some interest, Stengart v. Loving Care Agency, Inc., 2010 N.J. LEXIS 241 (March 30, 2010).
[W]e find that Stengart had a reasonable expectation of privacy in the e-mails she exchanged with her attorney on Loving Care’s laptop.
Stengart plainly took steps to protect the privacy of those e-mails and shield them from her employer. She used a personal, password-protected e-mail account instead of her company e-mail address and did not save the account’s password on her computer. In other words, she had a subjective expectation of privacy in messages to and from her lawyer discussing the subject of a future lawsuit.