At the end of the day whatever crime you are trying to get them for is occurring in the real world as well. All that physical evidence should help with convicti

At the end of the day whatever crime you are trying to get them for is occurring in the real world as well. All that physical evidence should help with convictions. When there is a murder, there is a body. When there is a rape, there is a victim. When there is a robbery, there are stolen goods. When drug trafficking has occurred, there are drugs. When there is child porn, there is a child involved. When there is a network breakin, there are server logs. When there is drug or bomb manufacture, there are raw materials. The police should be able to put people in jail based entirely on evidence of a crime without ever having to rely on anything a potential suspect has said or written. If that's the only way they can put someone away, I question how much of an actual crime has even occurred. If you can't come up with physical evidence, has society suffered enough harm for it to be even worth jailing that person? If all the physical evidence is still not enough for a conviction, then get a warrant and observe everything you can about that person of interest the old fashioned way. Eavesdrop on them with bugs (but don't remotely activate a backdoor in a phone that shouldn't exist). Stake out police officers at their house. Do undercover work. etc. Will some people get away with their crimes? Certainly. And that's okay. That's the cost society pays for their privacy. Police work is expected to be expensive. The cost of investigative work is something that provides checks and balances to abuse. A corrupt individual will have a very hard time hiding the misappropriation of police resources for political or personal reasons. If you need to stake out cops at a politicians house to get dirt on them to blackmail with, that probably won't happen. If you can just type an email into the system, then the barrier is so low to committing such an abuse and the likelihood of getting caught so low, that you can be sure that that abuse will happen. Also, keeping the cost high ensures that only those people who actually are terrorists, like active members of Al Quada are investigated. Right now the bar for investigation is so low that there has been a massive re-categorization of many domestic groups such as Occupy WallStreet as terrorists to be surveilled. I have absolutely no qualms with paying more taxes to hire more detectives as the alternative to making sure that we catch the terrorists. Having a high price to pay for investigations forces us as a society to ask the hard question of what we actually think is worth investigating and what is merely a nuisance for some that we can live with. Paying for those investigations with our privacy is entirely too high a cost.