Mr Anderson is quoted as saying:
"access to retained traffic and location data is extremely useful to the police and other law enforcement authorities, not only in the investigation of serious crime but e.g. for missing persons investigations where serious crime may not yet be suspected."
That is an argument which is repeated at multiple points in the article. What is not discussed however, is whether it is justified.
I think a personal experience of mine may be relevant here. I am currently involved in litigation against officials of the administration of a EU state, with the state being subsidiarily responsible. The crimes of which they are accused are serious (prison sentences of up to eight years are possible) and socially and politically sensitive. Had someone of lesser means than myself been the victim, it would have been a life-changing event for them--not exactly a positive one.
If data retention of the sort envisaged by DRIPA had been in place at the time, it would have been much easier for me, and for the public prosecutor, to prove the full extent of the crimes committed, and there would be much less leeway for the judge to impose a more lenient sentence.
In that sense, it cannot be argued that yes, indeed data retention would have been very useful.
However, would it be justified? No. Not at all. Even though as a victim I might have individually benefited from it once, I am convinced this does not legitimise the loss of important rights, both at an individual and social level. After all, the privacy rights of the individuals that I accuse are as valid as mine.
So if anyone is going to advocate data retention, please, not in my name.