[dragonwriter]

> This is true but it protects against "unreasonable" searches.

It prohibits unreasonable searches. Whether it protects against them depends on the effectiveness with which its prohibition is enforced. Unfortunately, enforcement through the courts has been effectively limited to the exclusionary rule, which is perhaps a reasonably sufficient remedy against unreasonable searches for the purposes of criminal prosecution [0], but is completely useless against unreasonable searches for other purposes.

[0] though perhaps not, there's all kinds of exploitable limitations to the exclusionary rule even in the criminal domain.