Yes. This thread is full of people proposing inventive technical solutions to genuinely prohibit your own access to the device while you're going through customs, as if border patrol a) knows the difference and b) gives a damn. These are all functionally equivalent to "Um, I forgot my password." (Or, if you wish for a more plausible but equally ineffective excuse, "This is actually my mother's laptop; I'm bringing it to her and I don't know the password.")
If an LEO (claims to) need access to something and you give him a dead end, it's his job to assume you're lying and find the next legal option available to him.
The real question you should be asking yourselves isn't "How would you outsmart the caveman cop in this situation?" Rather, it's "What can/will you do, as a citizen, to resist the erosion of our civil liberties?" Sadly, I have no easy answers here.