"Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it." - Source http://en.wikipedia.org/wiki/Copyright
One might argue that my words in a document are not property, however they are often refereed to as intellectual property (refers to creations of the mind for which exclusive rights are recognized in law). They are mine and I hold the exclusive rights to them. I want them back. What right does a government have to take them from me?
The term is "unreasonable search and seizure" and it is not considered unreasonable to search documents that someone voluntarily gave to a third party (e.g. a cloud hosting provider) with that third party's consent.
I think it depends on the legal agreements between the parties. Many hosting and service contracts make an effort to preserve an expectation of privacy.
