Why are those straw men? They're questions of universal applicability and jurisdiction, and both based on real things that have happened.
For example, the proposition that "MI5 should have access to the full communications history of everyone in the country" implies that as people enter the country MI5 should acquire their entire email history.
For example, you state that handing over data about Chilean users may result in them being murdered. I could just as easily argue that if you didn't hand over the data, Chilean users may be murdered. I'm not saying they will be or anything like that, obviously.
Compared to your last point, which is rooted in solid fact (They were both monitored, it did nothing to prevent the attack) and can't be argued with, the other two are a bit.. flimsy.
All I'm saying is if I was arguing against you (Which I'm not), it'd be easy to call you hysterical when you go on about murder and the Chinese.
For clarity, ignored your first point because not US and second point is sound, so I left that out as well :)
Ah I see - the inherent hypotheticalness of statements about the future. But as you say, the pro-surveillance case also rests on forward-looking statements about what the security services are going to do with the data.
In that case we have to go backwards. The National reminded me today of this incident: http://news.google.com/newspapers?nid=2507&dat=19860903&id=F... (Leon Brittan's involvment in politically motivated surveillance of CND). There's also the long and ugly history of Northern Ireland, and the more recent business of planting police informers in environmental groups.
The problem with trying to use recent history to prove a point is that everyone's already made up their mind which side they're on for things like extraordinary rendition, "School of the Americas", torture, Iran-Contra, arms-to-Iraq (Matrix Churchill), etc.
Matrix Churchill might be a good example, tbh. http://en.wikipedia.org/wiki/Scott_Report : MI5 instructed and secured secret permission for exports to Iraq, but then tried to protect the secrecy of this at the cost of not just allowing Matrix Churchill directors to be jailed but censoring their only legal defence and getting ministers to lie to parliament.
For example, the proposition that "MI5 should have access to the full communications history of everyone in the country" implies that as people enter the country MI5 should acquire their entire email history.