What are you warranting?
Normally, the contract will ask you to warrant that you are the true “sole and original” creator of the work. In case of a future dispute over rights, this shows that your publisher acted in a good-faith belief that you were the author/creator—because you warranted it was so.
Language to look for: “Author warrants that the Work is original with [you] . . . that [you are] the sole and original creator thereof”
This is different from authorship, because sometimes ownership of a work is not held by the person who created it. A common example is a work made for hire, in which the author is only an employee or contractor of the copyright owner. Ownership likewise might have been sold, bequeathed, granted, or otherwise transferred to someone beside the creator—like another publisher. Warranting ownership again indicates to your publisher that they are contracting in good faith.
Language to look for: “that the Author is the sole owner of the rights granted herein”
By warranting that you have the authority and power to make the agreement (to grant the rights you are granting in the contract), you are assuring your publisher that the work is not bound by legal constraints—as it would be if there were a lien on it, or if it were currently the subject of a legal dispute, like an inheritance or divorce.
Language to look for: “that the Author has full power and authority to make this agreement . . . that no right in the work has been sold, mortgaged, or otherwise disposed of; that the work is free from all liens and claims”
Many scholarly and some creative publications include or embed work that was created by someone else (including students). By warranting that you have permission to use the embedded work, you are assuring your publisher that you have cleared permissions with whoever controls the rights to reprint, or that you have not exceeded the bounds of fair use under the Copyright Act. Normally, you will need to provide originals or copies of written permissions during the editorial process.
Language to look for: “that the Work does not infringe any copyright or violate any proprietary rights”
Libel, unlawful, etc.
Often, the contract will include your formal warrant that your work contains nothing libelous or unlawful, that it does not infringe any rights belonging to others, and is not an invasion of privacy.
Exposure to a libel suit is one of the greater risks in publishing, so, in this clause, your publisher is asking for your formal warrant that what you have presented in the work as fact about other individuals or entities is indeed factual and documentable, and that where you are expressing opinions that might be objectionable, those are clearly represented as opinions.
Language to look for: “does not contain any scandalous or libelous matter, or invade the privacy of any person”