In order to protect the public interest and the free flow of information, the news media should have the benefit of a substantial privilege not to reveal sources of information or to disclose unpublished information. To this end, the freedom of press requires protection of the confidential relationship between the news gatherer and the source of information. The purpose of sections 595.021 to 595.025 is to insure and perpetuate, consistent with the public interest, the confidential relationship between the news media and its sources.