There is also the issue of parallel construction - basically using evidence gathered illegally to build a case, and then not submitting that evidence during the case, or using it for a plea-bargain.

As Snowden said, good encryption is a part defense against this. VeraCrypt http://veracrypt.org works nicely with DropBox, while SyncDocs https://syncdocs.com encrypts Google Drive.

Richelieu would have had a ridiculously easier time if he could select any six lines from everything an honest man had ever written. Using encryption to make this harder could be wise.