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From the San Francisco DUI Attorney Files: Police Stopping a Motorist

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May the Police Lawfully Stop A Motorist Based Solely On Somebody Reporting a Drunk Driver?

The key to beating a DUI charge in San Francisco---or at least getting a reduced offer on it---is to retain a local San Francisco DUI lawyer who specializes in this field. Such a lawyer will know the ramifications of a DUI conviction and how the California DMV will treat a drunk driving conviction. If you have one or more prior convictions for DUI or DWI (some states refer to it as "driving while impaired"), you want an attorney who is knowledgeable about the ways to attack prior convictions and the adequacy of out-of-state convictions.


When evaluating the constitutionality of a detention based on a tip to the police, one must preliminarily note the distinction between “anonymous tipsters” (folks who telephone the police about a crime, but do not identify themselves and are not known to the police), “government agents” (snitches working for the constable) and “citizen informants” (chance witnesses or crime victims who expose their identity). With regard to “anonymous tipsters” and “government agents,” there is no presumption of reliability attached to their reports. With “citizen informants,” however, there is a presumption of reliability, but even this presumption does not “dispense with the requirement that the informant—whether citizen or otherwise—furnish underlying facts sufficiently detailed to cause a reasonable person to believe that a crime had been committed....” People v. Ramey (1976) 16 Cal3d. 263, at 269.


From Chapter 7 of California Drunk Driving Law (James Publishing - Kuwatch, Burglin & Simons). Copyright 2011. All rights reserved. May not be reprinted without permission of publisher and authors.

If the officer making an enforcement stop does not know whether the tipster exposed his identity, then the source of the information must be treated as an “anonymous tip.” This is because the constitutionality of the detention turns on what the officer knew prior to the enforcement stop, People v. Ramey (1976) 16 Cal3d. 263, 268, and “a police officer can legally stop a motorist only if the facts and circumstances known to the officer support at least a reasonable suspicion that the driver has violated the Vehicle Code or some other law.” People v. Miranda (1993) 17 Cal.App.34th 917, 926 (emphasis added).

All that being said, however, an anonymous and uncorroborated phone tip about a potential drunk driver may trigger the “public safety” exception to the Fourth Amendment, even where the police do not independently observe anything unusual about the motorist or his driving prior to the enforcement stop. People v. Wells (2006) 38 Cal.4th 1078 (Docket No. S128640).

The Wells Court presumed the caller was anonymous because of a silent record on this point. The dispatcher broadcasted “a possibly intoxicated driver ‘weaving all over the roadway,’” and described the vehicle as an “80’s model blue van traveling northbound on Highway 99 at Airport Drive.” The officer, who was heading southbound 3 to 4 miles away from that location when he got the call, positioned himself on the shoulder of northbound Highway 99. “Two or three minutes” later he saw a blue van traveling approximately 50 miles per hour. He made an enforcement stop without independently observing any unusual, suspicious, or illegal driving.

Citing “the grave risks posed by an intoxicated highway driver,” the Wells Court held in a 4-3 decision that a brief, investigatory stop was justified under the circumstances. While approving a lower court ruling in Lowry v. Gutierrez (2005) 129 Cal.App.4th 926, and following a non-binding federal opinion in United States v. Wheat (8th Cir. 2001), 278 F.3d 722, the Court declared that “there is a sound and logical distinction between the vehicle stop in the present case and the frisk found unconstitutional in [Florida v. J.L. (2000) 529 U.S. 266 (anonymous tip reporting a young, African-American man in a plaid shirt, standing at a particular bus stop and carrying a gun)]. Seizing on J.L.’s statement that there may be “circumstances under which the danger alleged in an anonymous tip might be so great as to justify a search even without a showing of reliability...[such as a report] of a person carrying a bomb...,” J.L., at 273-274, the Wells Court found that a “drunk driver is not at all unlike a bomb, and a mobile one at that [citing the Vermont Supreme Court in State v. Boyea (2000) 765 A.2d 862, 867-868].”

As in Wheat, the Court further found that the tip’s lack of “predictive information” was not critical to determining its reliability. It also cited Michigan Department of State Police v. Sitz (1990) 496 U.S. 444, 455, for the proposition that the high Court has sanctioned the “stopping of all drivers to investigate possible drunk driving despite any articulable facts indicating an immediate risk of harm.”

In a well-reasoned dissent, J. Werdegar (joined by J. Kennard and J. Moreno) took the slim majority to task for its attempt to distinguish the circumstances from those in J.L., and for “unpersuasively [attempting] to fit this case into a possible exception mentioned by the J.L. court.” She mocked them for simply “assuming that the tip came from another driver with personal knowledge defendant was weaving all over the roadway,” when there was nothing in the record to support that assumption. She noted that Sitz, supra, involved the detention of every motorist, and that the Sitz Court had specifically noted that the “‘detention of particular motorists for more extensive field sobriety testing may require satisfaction of an individualized suspicion standard.’ (Id. at 451, italics added).”

The dissent further declared, however, that “[h]ad the police obtained the name and telephone number of the tipster, this would be a different case.” Furthermore, that “[t]he observation of even a small deviation, such as weaving slightly within a lane, may, when coupled with the anonymous tip, have been sufficient to justify a traffic stop.”

The lawfulness of a detention based on a tipster’s report of a drunk driver had splintered the appellate courts in California since the U.S. Supreme Court’s seminal decision in J.L. which rejected the argument that the mere prompt verification of the description of a particular person, at a particular location, renders a tip sufficiently reliable, holding that the reasonable suspicion standard “requires that a tip be reliable in its assertion of illegality, not just in its tendency to identify a determinate person.” Id., at 272.

J.L. distinguished its ruling from Alabama v. White (1990) 496 U.S. 325, where the Court upheld a detention based on an anonymous tipster’s report that a woman carrying cocaine would be leaving an apartment building at a specified time, get into a particularly described vehicle, and drive to a named motel. The White ruling, in what the high Court said was a “close call,” turned on the trial court’s finding that police observation after the tip showed that the informant had accurately predicted the woman’s movements, whereas the tipster in J.L. only reported that the suspect was hanging around a certain bus stop (i.e., it provided no predictive information, leaving the police without any means to test the informant’s knowledge or credibility). “If White was a close case on the reliability of anonymous tips, this one surely falls on the other side of the line,” wrote Ruth Bader Ginsburg for the majority. With that comment, the majority clearly indicted that the warrantless detention in J.L. was not even a close call in terms of being unconstitutional.

Until Wells, J.L. seemed to abolish California’s “Willard rule”—that a drunk driving detention is legal where a tipster simply uses the magic words, “he’s drunk,” and points out a motorist to the police. People v. Willard (1986) 183 Cal.App.3d Supp. 5. Wells arguably resurrected the Willard rule. In People v. Dolly (2007) 40 Cal.4th 458, the California Supreme Court held that an anonymous 911 tip contemporaneously reporting an assault with a firearm and accurately describing the perpetrator, his vehicle, and its location is sufficient to justify an investigatory detention. The Dolly Court distinguished its holding from Florida v. J.L., on the basis that a violent crime was reported as having just taken place. The tipster also gave reasonable explanation (his fear of perpetrator) for not identifying himself. See also, People v. Lindsey (2007) 148 Cal.App.4th 1390 (anonymous tipster reported that defendant fired gun—detention upheld); Lowry v. Gutierrez (2005) 129 Cal.App.4th 926 (anonymous tip deemed legally sufficient basis to detain a motorist, though Court said it was a close call and noted that a precise description of the driver’s actions (wrong way driving and left turn into oncoming traffic) had been described by the caller.

The Dolly decision overrules People v. Jordan (2004) 121 Cal.App.4th 544 (even a 911 call with extensive detail about a man with a gun was held to be an insufficient basis for a warrantless patdown where the caller was not known to the officer).

People v. Rodgers (2005) 131 Cal.App.4th 1560 rev. granted, involved an anonymous tipster reporting a man with a gun in a car threatening to kill his female passenger. Following Lowry, supra, the Court held that a moving vehicle creates an exigency not present in J.L., supra. Likewise, People v. Castro (2006) 138 Cal.App.4th 486, held that an anonymous tipster’s report of a driver, threatening to kill his wife, amounted to an exigent circumstance justifying a traffic stop.

In People v. Saldana (2002) 101 Cal.App.4th 170, the court held that an anonymous tipster calling from a pay phone did not justify a stop, detention and search. The anonymous telephone tip did not include predictive information and the observed corroboration that a vehicle fitting the description was indeed present at the described location did not corroborate the criminal element of the tip. This drug case does not involve, however, the report of a drunk driver (though it does involve a man with a gun and a kilo of cocaine!).

Thus, what the Supreme Court teaches in Gates [Illinois v. Gates (1983) 462 U.S. 213], White [Alabama v. White (1990) 496 U.S. 325], and J.L. [Florida v. J.L. (2000) 529 U.S. 266], is that in order for an anonymous tip to serve as the basis for reasonable suspicion: (1) the tip must include a “range of details;” (2) the tip cannot simply describe easily observed facts and conditions, but must predict the suspect’s future movements; and (3) the future movements must be corroborated by independent police observation.


In dealing with a tipster issue, the following are some important things to consider:

- Was the report made by an anonymous tipster, government agent, or citizen informant?

- Was the call made to a general police line or to an emergency (e.g., 911) line?

- Did it sound like the caller was speaking under the stress of excitement?

- To what extent did the caller identity the suspect and the vehicle?

- Did the caller describe the basis for his conclusion that the suspect was drunk or impaired, and if so, to what extent?

- Did the caller give predictive information about the suspect’s future movements?

- What facts, if any, heightened the need for immediate action (e.g., driving through a carnival or out on some country road)?

- Did the officer independently observe anything about the suspect or the vehicle that gave him grounds to make an enforcement stop?

Remember that the prosecution bears the burden of proof when it comes to a warrantless detention, and that the constitutionality of a detention is determined by what the officer knew at the time he made the stop. It is often wise to not ask a question in a Pen. C. §1538.5 motion to suppress hearing where the evidence has not yet proven a particular point.

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