Prisoners eligible for transfer from Mexico to the United States must be citizens of the United States; be convicted and sentenced; have no appeals or collateral attacks upon conviction pending; have at least 6 months of the sentence remaining to be served; be convicted of an offense that is not an immigration, military, or political offense; and be convicted of an offense that is generally punishable as a crime under the laws of the United States. They must not have been living in Mexico for 5 years or more prior to the arrest, and have the consent of the American and Mexican Goverments. Once back in the United States, prisoners may not challenge their conviction under Mexican law; however, they may petition the Mexican Government for pardon or commutation of sentence. Prisoners must acknowledge in writing that their transfer was voluntary and intelligent. Thereafter, they cannot challenge the transfer on the grounds that they would have said anything to get out of Mexico and that their consent was not voluntary. Prisoners may challege the constitutionality of the treaty in some other way, and they may also challenge the procedures under which they were transferred. There is very little effect of a foreign conviction under Federal law, but the effect of a foreign conviction can vary from State to State. Appendixes include a list of helpful organizations, various guidelines, and the treaty.