Despite what people feel are laws protecting your privacy. With the exception of your employer placing video cameras in the nathrooms, you really have NO privacy in a place of business.
your company doesn't need a formal policy to manage the misuse of company equipment.
One thing that is strong in America is how people are constantly feeling that they have rights that are applicable no matter where they are.
your company can protect its business investment without any legal repercussions.
If your employer feels that you are using THEIR internet connection in a way that could jeopardaize security, defame the company, or in a way that is detracting from your work, they can monitor your actions and or fire the abuser immediately without notice.
Misuse of company property is reason for immediate dismissal no matter what your formal agreements may be.
This can also be construed as theft if the person is using the internet for his/her own benefit that is not in the bestinterests of the company.
Being charged for theft from your company, I don't think you'd have much hope in screaming about your personal privacy being invaded!
Start thinking about what your responsibilities to the company are and forget about your "Personal privacy" protection, at least until you fully understand corporate laws. In this case, if you were to compain that your so called "personal privacy" had been compromised while downloading Debbie Does Dallas on your corporate network that the company pays for and maintains, you would find yourself on America's Funniest Home Videos in no time.
Invasion of privacy??? You've got to be kidding!
When it comes to your actions on Company premises, with Company equipment that the company has paid for, you have NO personal connection to the system and therefore NO personal privacy is being invaded when the company monitors the use of it's equipment.