It seems some court say "inability to produce documentation does not in itself provide probable cause (to arrest)."
"The disappointing aspect of Gonzales is the statement that an alien's "inability to produce documentation does not in itself provide probable cause (to arrest)." See Gonzales v. City of Peoria, supra, at 16. Pursuant to 8 U.S.C. § 1304(e), aliens are issued registration cards and must carry such cards with them at all times. Aliens who gain entry without the requisite inspection, and who therefore are not issued such cards, violate 8 U.S.C. § 1325. Consequently, a law enforcement officer confronting an alien who is unable to produce documentation arguably has probable cause to believe that a violation of 8 U.S.C. § 1304(e) (failure to possess documents or 8 U.S.C. § 1325(a) (entry without inspection) has occurred. (If the alien is undocumented and has been in the United States for longer than 30 days, he or she has also violated 8 U.S.C. § 1306(a))."