Why not going for encryption? The reasons usually provided by detractors aren't satisfying: "Police needs to access consumer data because they need to investigate terrorism". This is false because the police doesn't even use the current investigation methods. For example:
France and Belgium were recently submitted to terrorists attacks. The police didn't have detectives for such terrorist cells in the first place, so full access to citizen's privacy wouldn't have helped if there was no investigation going on. You won't believe how simple is the root cause: Any organization is dedicated to justifying its growth, so police will constantly request for an upgrade of their gear, people and scope, such as computing methods to solve petty crime, while policemen have no incentive to risk their lives to investigate terrorism on the field. They, unfortunately, have no incentive in solving terrorism, because it will always be legitimate to say 'Oops, this terrorist cell wasn't detected, give us more means and people so we do better next time'. On the other hand, terrorists know very well how to protect their data, and it gives policemen huge pride and power to have access to citizen's private data - just check how many US policemen were condemned for stalking a girlfriend last year. So police access to private data is not going to solve terrorism, because there aren't enough forces dedicated to investigation anyway.
Another example: France has signed the Shengen agreement, which says it's better to join our police forces to protect the borders of Europe instead of each country protecting its own. Fast forward 30 years, we've let about 2 million illegal immigrants through, including ALL our terrorists who were born in France, went to Syria for military training and back. Talk about porosity! People with military training from an ennemy force are supposed to be arrested under Geneva conditions; They were well known and listed by our files, some of them were arrested by Turkey and given to Europe handcuffed and person-to-person, and freed later by European police for lack of means. So you see, there is not even a need for police to access to all SMS and phone calls. We weren't doing anything against terrorism in the first place. We've been lied to by politicians.
Also note that the US has become a police state and levied all their privacy protections since 2001. Did it solve terrorism? 2013: Boston attacks.
Terrorism isn't something police can reduce in the first place. Besides, going to foreign countries to destroy houses and spread poverty will only accelerate it, especially when using drones and non-judicial decisions. I'm flommoxed that France goes to Syria, because our terrorists were born in France. The only 3 things that eventually reduces candidates to terrorism:
- Investigations where police forces risk their lives. Not going to happen.
- For western-born terrorists: Good education, career prospects, loving wife and children. No racism. Not going to happen.
- For foreign countries: No Predator, no drones, no american/european attacks, no spies, no Israel expansion, just lest we parachute schools and books and food and toys for toddlers and education for women. Joint development. Remember the Marshall plan? We need to learn to forgive again. Not going to happen soon.
So don't expect terrorism to be over any soon. It's one of the risks of life, among with drugs, second-hand smoking and heart strokes.
On the other hand, the risk of not encrypting is to give people in power more information, and centralizing power even more, to the dismay of social mobility. For example, the #PanamaPapers couldn't have been investigated if police had access to journalists' communications, because they would have gently asked them to shut up.