Flores-Villar (D) was born in Tijuana, Mexico on October 7, 1974, to Ruben Trinidad Floresvillar-Sandez, his United States citizen biological father who was sixteen at the time, and Maria Mercedes Negrete, his non-United States citizen biological mother. Floresvillar-Sandez had been issued a Certificate of Citizenship on May 24, 1999, based on the fact that his mother-Flores Villar's paternal grandmother-is a United States citizen by birth. Flores-Villar was convicted of importation of marijuana in violation of 21 U.S.C. §§ 952 and 960; and was also convicted of two counts of illegal entry into the United States in violation of 8 U.S.C. § 1325. He was removed from the United States. D was arrested again and this time was charged with being a deported alien found in the United States after deportation in violation of 8 U.S.C. § 1326(a) and (b). D sought to defend on the grounds that he believed he was a United States citizen through his father. D filed an N-600 application seeking a Certificate of Citizenship, which was denied on the ground that it was physically impossible for his father, who was sixteen when Flores-Villar was born, to have been present in the United States for five years after his fourteenth birthday as required by § 1401(a)(7). The United States (P) filed a motion in limine to exclude evidence of derivative citizenship. The district court found D guilty. D appealed. Under the current immigration law, if a United States citizen father had a child out of wedlock abroad, with a non-United States citizen mother, the father must have resided in the United States for at least five years after his fourteenth birthday to confer citizenship on his child. But a United States citizen mother had to reside in the United States for a continuous period of only one year prior to the child's birth to pass on citizenship. D contends that this is an impermissible classification on the basis of gender and age.