On 12 March 1844, presumably at JS’s direction, was authorized to act as an for the city council of , Illinois, in . The previous December, JS proposed to the members of the city council that they petition Congress to protect the city. In response, a committee drafted a memorial requesting that Nauvoo be granted all the powers and rights belonging to a federal territory of the until provided redress for the losses the had sustained in the state in the 1830s. The memorial also asked that the mayor of Nauvoo be authorized to call upon federal troops as necessary to help the repel mobs and keep the peace. The city council accepted the memorial on 21 December 1843 and signed it on 12 February 1844. Pratt was appointed to travel to Washington DC to deliver the memorial to Congress. Shortly after receiving this authorization, Pratt departed Nauvoo for Washington to complete his assignment.

The featured version of the authorization, which was inscribed by , bears the notation “copy,” suggesting that it was a draft or a retained copy of the version that took with him to . A docket in ’s handwriting suggests that Richards inscribed the original letter at JS’s request. JS signed the copy of the authorization, as mayor, and Richards also signed it, as city recorder. This version was later repurposed as a copy of an authorization for by , who changed the date and the name of the subject of the letter. The document is the only extant version of Pratt’s authorization.