250 word discussion including two references

The line drawn to mark where and/or when you have a "reasonable expectation of privacy" can get quite fuzzy, particularly in this age of evolving technology.

Scenario: Your government employer seeks to search, without a search warrant, the records and transcripts of the text messages you had sent on an employer owned device (cell phone, etc.) or the information and e-mails stored on a computer in your government office. What are your arguments for claiming that you had a reasonable expectation of privacy, and that the searches violated the 4th Amendment?

Let's change the scenario a bit - What about private text messages or e-mails sent to your spouse from the same government owned devices, but while you were at home and off duty?

Finally, what about private data, images or information stored on a personally owned thumb drive that you attached to a government owned device?