                                                       United States Court of Appeals
                                                                Fifth Circuit
                                                             F I L E D
               IN THE UNITED STATES COURT OF APPEALS
                       FOR THE FIFTH CIRCUIT                 August 17, 2005

                                                          Charles R. Fulbruge III
                                                                  Clerk
                            No. 04-41088
                        Conference Calendar



UNITED STATES OF AMERICA,

                                    Plaintiff-Appellee,

versus

JUAN MANUEL PENA,

                                    Defendant-Appellant.

                       --------------------
          Appeal from the United States District Court
               for the Southern District of Texas
                      USDC No. 5:04-CR-75-1
                       --------------------

Before BENAVIDES, CLEMENT, and PRADO, Circuit Judges.

PER CURIAM:*

     Juan Manuel Pena appeals the 51-month sentence imposed

following his guilty-plea conviction for conspiracy to possess

with the intent to distribute more than 100 kilograms of

marijuana, in violation of 21 U.S.C. §§ 841 and 846.     He argues,

for the first time on appeal, that in light of Apprendi v. New

Jersey, 530 U.S. 466 (2000), the drug-trafficking statutes under

which he was convicted are facially unconstitutional because they

treat drug type and quantity as sentencing factors rather than


     *
       Pursuant to 5TH CIR. R. 47.5, the court has determined that
this opinion should not be published and is not precedent except
under the limited circumstances set forth in 5TH CIR. R. 47.5.4.
                           No. 04-41088
                                -2-

elements of the offense which must be pleaded and proved beyond a

reasonable doubt.   As Pena concedes, his argument is foreclosed

by United States v. Slaughter, 238 F.3d 580, 582 (5th Cir. 2000).

     In a supplemental letter brief, Pena additionally argues,

also for the first time on appeal, that his sentence should be

vacated because it was imposed pursuant to a mandatory

application of the sentencing guidelines, citing United States v.

Booker, 125 S. Ct. 738 (2005).   This argument is reviewed for

plain error.   United States v. Valenzuela-Quevedo, 407 F.3d 728,

733 (5th Cir. 2005), petition for cert. filed (July 25, 2005)

(No. 05-5556); see also United States v. Mares, 402 F.3d 511, 520

(5th Cir. 2005), petition for cert. filed (Mar. 31, 2005) (No.

04-9517).   To demonstrate plain error, Pena must show “(1) error,

(2) that is plain, and (3) that affects substantial rights.”

Mares, 402 F.3d at 520.   Following Booker, a sentence imposed

under the formerly mandatory, now advisory, guidelines regime

constitutes an error that is plain.   Valenzuela-Quevedo, 407 F.3d

at 733.   However, Pena has not demonstrated a probability that he

would have received a lower sentence under an advisory scheme,

and he has thus failed to demonstrate that the error affected his

substantial rights.   See id. at 733-34; see also Mares, 402 F.3d

at 521.   Accordingly, the district court’s judgment is AFFIRMED.
