The immigration authorities cannot lawfully lodge an immigration detainer against a person on the basis of a plea without sentence, and cannot lawfully begin removal proceedings on the basis of such a plea, for two reasons.  First, a conviction does not exist for immigration purposes until sentence has been imposed.  See § 7.20, supra.  Second, the conviction is not yet final in most circuits for immigration purposes until the period within which a direct appeal can be filed has elapsed, or until the court has rendered a final judgment on appeal affirming the conviction and the direct appeal has been concluded.  See § 7.37, supra.

Second Circuit

SENTENCE - DATE OF CONVICTION - SENTENCE REQUIRED TO CONSTITUTE CONVICTION
Puello v. BCIS, 511 F.3d 324 (2d Cir. Dec. 20, 2007) (under INA 101(f)(8), 8 U.S.C. 1101(f)(8), the date of conviction is the date of sentence: "In sum, we hold that, under the plain meaning of the definition of "conviction" in 8 U.S.C. 1101(a)(48)(A), the entry of a "formal judgment of guilt . . . by a court" occurs when judgment is entered on the docket, not when a defendant pleads guilty."); see Perez v. Elwood, 294 F.3d 552, 562 (3d Cir. 2002) (the date of conviction under the INA is the date of either sentencing or entry of judgment on the docket); Abimbola v. Ashcroft, 378 F.3d 173, 181 (2d Cir. 2004) (an Alford plea coupled with a sentence constitutes a conviction under the INA, and noting that "Congress focused the sanction of removal on a criminal conviction as opposed to an admission of guilt"); Mugalli v. Ashcroft, 258 F.3d 52, 62 (2d Cir. 2001) (in the deportation context, a New York state conviction mitigated by a Certificate of Relief is still a conviction under the INA because the defendant "entered a plea of guilty, and the court entered a formal judgment of guilt").