Whether or not this interception is currently legal / illegal, this has been happening on a massive, global scale. The UK is just catching up to France / USA / Canada in this regard. The EU legislation on the books for Saas, ISPs to log all their traffic for an indeterminate time is also a huge cause for concern.
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Oh, and we have a law in the UK which makes it a criminal offence, punishable by 2-5 years in prison, to refuse to hand over the private key so that your data can be decrypted. :(
That does not make me fell much safer. In Sweden there is nothing preventing illegally obtained evidence to be used in court. The idea is that the one obtaining the evidence will also be punished for his crimes, but I can easily see that case not even reaching court.
Why is it better to have this thing legislated? The argument that it is better to have laws like this because otherwise they will just do it anyway (illegally) just blows my mind. There are many advantages to having stuff like this unlegislated, without support from the law they can't actively act on the data, something that is far better than having the FRA-law. Especially when the intent of the law isn't to act on it but rather to observe.
In other words that argument is of the lines that "since they already have the information (which they illegally intercepted), why wouldn't we want to give them the legal right to intercept that information so that they act on it as well?". How does that make any sense?
Even with a warrant the data collected by FRA wouldn't be legal to use in a court if both parties (sender and receiver of a message/whatever) was in Sweden (regardless of whether the traffic took a detour across the border or not (too/from gmails servers for instance)).