Invasion of Privacy, or a Parental Right?

[momsunited]

My oldest is a tween (age 11 1/2), not yet a teen. But, we are getting closer, no doubt. She just suffered her first broken heart. A boy, her "buddy" and best friend moved away this weekend and she was heartbroken. More on a friend level than a first love level, but difficult just the same!
 
For now, we have fantantatic communication. I tell her to write out her feelings in her journal, and she does. It seems to help. She shares with me what she writes....for now....
 
My question is, one that I have been pondering a lot lately, is....as parents would you read your teen's private journal? Go through their things while they are away? For now she DOES still talk to me about everything, but I know the time is coming that she will pull away. Is it an invasion of privacy to go through their things to keep a handle on what is going on, or a parental right?
 
I am so new to this! I need some veteran Mama's to give me some personal insight! I am actually torn....