United States v. Tan Duc Nguyen, 673 F.3d 1259

Nguyen was charged in federal court with obstruction of justice for failing to disclose his full knowledge about the mailing of a letter that could be seen as voter intimidation.
The letter was mailed to foreign-born voters with Hispanic surnames registered as Democrats or declined to state, urging participation but warning about potential penalties.
State investigation by the California Attorney General linked Nguyen to the letter and led to a warrant for searches of his home and campaign HQ.
The search yielded emails and records showing Nguyen’s greater involvement in drafting and mailing the letter than he had admitted.
No state charges were filed; the federal case proceeded on obstruction of justice based on Nguyen’s statements to state investigators.
Nguyen moved to suppress the search evidence on the ground that the state warrant lacked probable cause; the district court denied the motion and he was convicted.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Was there probable cause to issue the state warrant?	Nguyen argues there was no fair probability of a crime.	Nguyen contends the affidavit failed to show a crime; insufficient nexus.	Yes; there was a fair probability that a California election-law crime occurred and evidence would be found.
Did the letter amount to a California election-law violation to justify probable cause?	Letter did not violate state law; no crime.	Contents could constitute violations under sections 18502, 18543, 18540.	Yes; the letter's content and targeted mailing created probable cause under 18540 and related provisions.
Does First Amendment protection apply to the challenged political speech?	The letter involves political speech with potential First Amendment protection.	California 18540 regulates true threats and intimidation; not protected when aimed to intimidate voters.	The warrant was properly issued; the statute fits true-threat framework and the facts supported probable cause.
Was the evidence suppression proper given the state warrant?	District court’s denial should be reversed if probable cause was lacking.	Probable cause existed; suppression not required.	District court properly denied suppression; evidence admissible.

Illinois v. Gates, 462 U.S. 213 (1983) (probable cause requires fair probability of crime and evidence in place)
United States v. Hill, 459 F.3d 966 (9th Cir. 2006) (nexus requires probability of crime and evidence in location)
Rubio, 727 F.2d 786 (9th Cir. 1983) (probable cause evaluated by Gates framework)
United States v. Celestine, 324 F.3d 1095 (9th Cir. 2003) (clear error review of magistrate’s probable cause determination)
United States v. Meek, 366 F.3d 705 (9th Cir. 2004) (probable-cause de novo review; suppression standard)
Hardeman v. Thomas, 208 Cal.App.3d 153 (Cal. Ct. App. 1989) (intimidation can be non-coercive; true threats concept)
United States v. Cassel, 408 F.3d 622 (9th Cir. 2005) (speech-restriction analysis for intimidation-related statutes)
Virginia v. Black, 538 U.S. 343 (2003) (true threats doctrine allowing regulation of intimidation)
Olagues v. Russoniello, 797 F.2d 1511 (9th Cir. 1986) (en banc; discussion of intimidating voting activity)
McLeod, 385 F.2d 734 (5th Cir. 1967) (federal statutes on voting intimidation depend on proscribed effect)