Modern communications surveillance policy is about gaining access to modern communications. The problem is that the discourse around communications policy today is almost the same as it was when it was simply a question of gaining access to telephone communications. "Police need access to social network activity just as they have access to phone calls" is the politician's line. We use Facebook as an example here, but most internet services will be similar in complexity and legality.
The reality is much more complicated, and modern communications surveillance policy hides far greater ambitions. Telcos usually have physical offices in the countries in which they operate and will comply with the law of the jurisidiction in responding to law enforcement requests. Social networking service providers tend to be based in just a few countires, despite having users all over the world, and are not therefore necessarily obliged to comply with domestic legal regimes.