I have three teenage boys. They are good boys, for the most part, and we have good, mutual communication and conversations. Many other parents tell me they read their teenagers' messages on a regular basis. I feel this is an incredible invasion of privacy. I remember my mother reading my diary and how upset I was that I could not write my feelings down in private.
If my sons were giving me reasons to monitor their conversations, I would, but just opening their messages for no reason seems flat-out wrong. Other parents tell me, "That's how you find stuff out."
Am I out of parental touch by respecting my sons' electronic boundaries?
Answer: I could argue that the parentally out-of-touch mantle belongs on the parents who use spying to know their own kids.
Regardless - the only way to raise responsible children is to grant them freedom in appropriate increments. The only way to do that is to assume the risk that you'll grant them too much freedom too soon.
It's also safe to assume kids, especially older ones, won't be eager to report their mistakes.
With these in mind, parents have two choices: (1) trust their children, at the risk of not catching a big mistake or abuse of trust until it's too late; or (2) choose not to trust their children, at the risk of damaging the children's trust in parents not to abuse their power. Not to mention damaging children's trust in themselves, and the confidence and motivation that trust promotes.
If neither choice announced itself as the lesser of two evils, try this - regular snooping is a certain, serious violation of their trust for the sole purpose of finding possible, possibly serious violations of your rules. On the other hand, kids who realize they've let down parents who trusted them often are then motivated not to disappoint them again.
And if it's still a toss-up, I offer the Fourth Amendment, condensed into your own words: "If my sons were giving me reasons to monitor their conversations, I would." These other parents might believe the fact of being a teenager constitutes probable cause; however, when they set the bar that low, they can't be surprised when their children obligingly stoop to reach it.