The final draft of the Declaration was written by John Dickinson, who incorporated language from an earlier draft by Thomas Jefferson. Objectionable causes were described in the declaration, such as taxation without representation and non-address of the colonists' grievances.
An initial draft was reportedly written by John Rutledge, a member of a committee of five appointed to create the Declaration. (1)
(1) Source for this post: The Declaration For the Causes and Necessity of Taking Up Arms