I'm not a lawyer, cybersecurity expert, or Apple technician, so I can't speak to the legal or scientific technicalities of this debate. I have spoken to some very tech savvy friends, and I've read analysis from computer tekkies and cybersecurity experts.
Basically, I'll approach this from a hypothetical standpoint. Discuss the issue in principle. For instance, I'm less concerned with what the law actually allows, but what it ought to allow.
1. I don't presume that Tim Cook is any kind of hero. I doubt he's really that high-minded. But he happens to be staking out the right position in this particular case, whatever his ulterior motives may be.
2. Not coincidentally, this case isn't about preventing a terrorist attack, but responding to a terrorist attack. The authorities have proven, time and again, that they won't protect us from terrorists. That's because, to prevent terrorist attacks, they'd have to profile Muslims, which is politically verboten.
Once you take profiling off the table, the alternatives are to turn a blind eye, wait for a terrorist to strike, or engage in dragnet surveillance.
3. Apropos (1), this is not a case of balancing liberty and security. Rather, we lose both. We're not trading liberty for security. For the authorities refuse to protect us. We've had a spate of jihadist attacks on American soil since Obama became president.
Every terrorist attack gives the gov't a pretext to eavesdrop on Americans in general. You end up with a police state. That doesn't make the general public safer. It creates a corrupt, law-enforcement culture that's unaccountable to the public. It turns law enforcement into an occupation force.
4. Regarding the security issue, from what I've read, the FBI is, in effect, demanding that Apple make a master key to open a particular safe. Problem is, that key can then be used to open any safe of the same make or model.
This is the same gov't with a rogue NSA. The same gov't that won't even defend its own database from Chinese hackers. And Apple is supposed to create a backdoor for that gov't?
5. Regarding the legal aspects, consider the very stretchy definition of a search warrant.
i) Isn't a search warrant judicial authorization to examine a person or place to discover contraband, stolen property, incriminating evidence, &c.?
But the phone in question isn't Apple's property. It's not in Apple's possession. It's not on Apple premises. Rather, it belonged to the gov't agency that issued the phone to the decedent.
ii) Does the gov't have the right to order Apple to design custom software to hack this model phone? Since when does the gov't have the right to order a company to make a particular product? Ordering a company to produce custom software is hardly equivalent to a search warrant.
iii) Isn't hacking illegal? Isn't the gov't ordering Apple to break the law? Or facilitating a crime. Even if US law contains exemptions for criminal investigators, surely there are international laws against hacking. How would international law exempt American criminal investigators?
For further analysis: