Endangered Species Listing and Delisting Process Reform Act of 2003

Endangered Species Listing and Delisting Process Reform Act of 2003 - Amends the Endangered Species Act of 1973 to require the Secretary of the Interior to use data that are empirical or have been field-tested or peer-reviewed in any case in which such Act requires the Secretary to use the best scientific and commercial data available in the determination of a species for inclusion on the endangered or threatened species list.

Requires the Secretary to: determine that a species is an endangered or threatened species only if there is sufficient biological information to support recovery planning for the species.

Specifies information required in a petition to add a species to the endangered or threatened list. Requires the Secretary to notify and provide a copy of a petition to the State agency of each State in which the species is believed to occur and to solicit the assessment of such agency as to whether the petitioned action is warranted.

Directs the Secretary, upon publication of a proposed regulation determining an endangered or threatened listing, to make publicly available all information on which the determination is based, as well as all information relating to the species that does not support such determination (with an exception for disclosures protected under the Freedom of Information Act or the Privacy Act).

Requires the Secretary to promulgate regulations that establish criteria that must be met for scientific and commercial data to be used as the basis for a determination that a species is an endangered or threatened species.