Dog Sniff Evidence in Civil Asset Forfeiture Cases

In many civil asset forfeiture cases involving the seizure of U.S. Currency, the seizure occurs at the airport or on the roadside. Officers often use a K9 drug dog sniff to justify the warrantless search and seizure. But how much weight should be given to a positive alert by the drug dog?

Courts are wary of the persuasiveness of dog sniff evidence in light of a concern that much of the currency in circulation contains sufficient quantities of narcotics to prompt an alert. In United States v. $506,231 in U.S. Currency, 125 F.3d 442, 453 (7th Cir. 1997), the court found that the “probative value of dog sniffs is, at most, minimal.”

Uncritical Adoption of the “Currency Contamination Theory”

The courts have taken the view that “a properly trained dog’s alert to currency should be entitled to probative weight.” $30,670, 403 F.3d at 459. In that case, the court concluded that a positive dog sniff was “strong probative evidence of illegal narcotics activity.” Id. at 470.

The court reached that conclusion after consulting scientific research indicating “that circulated currency, innocently contaminated with [microgram] quantities of cocaine would not cause a properly trained detection canine to signal an alert even if very large numbers of bills are present.” Id. at 459.

The court explained that other cases, including $506,231, relied on an “uncritical adoption of the currency contamination theory.” 403 F.3d at 459. For this reason, dog sniff evidence might provide some minimal evidence to help the Government satisfying its initial pleading burden.

Dog Sniffs Provide, at Most, Minimal Evidence

In United States v. $8,221,877.16 in U.S. Currency, 330 F.3d 141, 157 (3d Cir. 2003), the court granted a motion to dismiss for failure to state a claim after finding the complaint lacked probable cause. The court discounted evidence of the dog sniff while noting:

…the positive dog sniff would not be admissible at trial to establish probable cause and therefore the government cannot use it to support its forfeiture claim. While it is true that the government need not possess all of the information required to establish probable cause for the forfeiture at the initial seizure, $ 53,082.00, 985 F.2d at 250, the government must still possess probable cause to justify the initial seizure of currency carried on claimant’s person. Id. at 249.

Probable cause “means [a] ‘reasonable ground for belief of guilt, supported by less than prima facie proof but more than mere suspicion.'” United States v. $ 67,220 in United States Currency, 957 F.2d 280, 284 (6th Cir. 1992) (internal citations omitted).

The initial seizure here was based entirely upon the fact that Sanchez fit the drug-courier profile. This does not support probable cause for the seizure of defendant funds since the “drug courier profile . . . lists behavior which can be attributable to perfectly legal activities, as well as illicit ones.” $ 53,082.00, 985 F.2d at 249.

Where evidence is obtained that is the product of an illegal initial seizure it is subject to exclusion at the forfeiture proceeding. One 1958 Plymouth Sedan v. Pennsylvania, 380 U.S. 693, 702, 14 L. Ed. 2d 170, 85 S. Ct. 1246 (1965).

Therefore, only legally-obtained evidence may be used to establish probable cause. $ 53,082.00, 985 F.2d at 250. Here, the positive dog-sniff evidence cannot be used to show probable cause because it is the fruit of an illegal seizure and as such must be excluded.

Even if the dog sniff in this case was not excludable as the fruit of an illegal seizure, we would refuse to find that it is a sufficient basis to establish probable cause.

A growing number of courts have agreed that “the presence of trace narcotics on currency does not yield any relevant information whatsoever about the currency’s history.” Jones v. United States Drug Enforcement Admin., 819 F. Supp. 698, 720 (M.D.Tenn. 1993); see $ 53,082.00, 985 F.2d at 250, n.5; United States v. $ 639,558.00 in United States Currency, 293 U.S. App. D.C. 384, 955 F.2d 712, 714, n.2 (D.C.Cir. 1992); $ 80,760.00, 781 F. Supp. at 475-77 (N.D.Tex. 1991).

Although the studies which have been conducted disagree with respect to the percentage of bills contaminated, it cannot be doubted that contaminated currency is widespread. Jones, 819 F. Supp. at 720.

There is some indication that “residue from narcotics contaminates as much as 96% of the currency currently in circulation.” $ 80,760.00, 781 F. Supp. at 475 & n.32.

“Given these facts, the continued reliance of courts and law enforcement officers on dog sniffs to separate “legitimate” currency from “drug-connected” currency is logically indefensible. 819 F. Supp. at 721.

Further, a string of court decisions indicates that probable cause for forfeiture requires the government to do more than merely subject currency to a drug dog search. See $ 80,760.00, 781 F. Supp. at 476; United States v. $ 53,082.00 in United States Currency, 773 F. Supp. 26, 33-34 (E.D.Mich. 1991); United States v. $ 13,000 in United States Currency, 747 F. Supp. 430, 433 (S.D.Ohio 1990); In re Forfeiture of $ 18,000, 189 Mich. App. 1, 471 N.W.2d 628 (Mich.Ct.App. 1991). Therefore, the government’s allegation that a narcotics detection dog alerted to the seized funds does not suffice to state a cause of action for forfeiture.

Id. at 1263-64.

This article was last updated on Thursday, September 17, 2026.