In the
 United States Court of Appeals
              For the Seventh Circuit
                        ____________

No. 05-3761
UNITED STATES OF AMERICA,
                                            Plaintiff-Appellee,
                              v.

DEMARCO L. MCDONALD,
                                         Defendant-Appellant.
                        ____________
          Appeal from the United States District Court
               for the Southern District of Illinois.
          No. 05 CR 30007—William D. Stiehl, Judge.
                        ____________
   ARGUED FEBRUARY 13, 2006—DECIDED JULY 17, 2006
                   ____________


  Before KANNE, EVANS, and WILLIAMS, Circuit Judges.
  WILLIAMS, Circuit Judge. Demarco McDonald was
arrested for possession of a firearm by a felon, in viola-
tion of 18 U.S.C. § 922(g)(1). Police found a gun in his car
when they stopped him for using his turn signal while
rounding a bend in a street. After the district court denied
his motion to suppress evidence seized as a result of the
stop, McDonald entered a conditional guilty plea reserving
his right to appeal the denial of his motion to suppress.
McDonald contends on appeal that his use of the turn
signal was not illegal under Illinois law and that a police
officer’s mistaken belief about the law could not sup-
port probable cause for his arrest. We agree and therefore
reverse the decision of the district court.
2                                                No. 05-3761

                    I. BACKGROUND
  On November 20, 2004, Belleville, Illinois police officers
Michael Pearce and Timothy Lay stopped McDonald’s car
after they received an anonymous tip and believed McDon-
ald fit the description. As Officer Pearce approached
McDonald, he noticed a gun on the floor of the car. Because
McDonald had previously been convicted of a felony, he was
charged under § 922(g)(1) for being a felon in possession of
a firearm. McDonald moved to suppress evidence pertain-
ing to the gun, initially arguing that the officers should
not have pulled him over because the anonymous tip alone
was not sufficient evidence to provide probable cause to stop
him. The government responded, however, that McDonald
was actually stopped because he used his turn signal but
never turned onto a different street. The officers believed
that was a traffic offense under 625 Ill. Comp. Stat. 5/11-
804(d) (2005). McDonald responded that § 5/11-804 did not
prohibit his actions and that Officer Pearce’s mistake of law
could not justify a traffic stop.
   Officer Pearce testified at the hearing on the motion,
stating that the police received a tip claiming that a
black male driving a maroon Buick possessed drugs and a
handgun. Later that night, the officers saw a car match-
ing that description and began to follow it. When the driver
flashed his turn signal at a ninety-degree curve in the road
where the road changed names, Officer Pearce stopped the
car. He testified that he consulted his “Offense Code Book”
(a guide for police officers that catalogs traffic laws), which
listed an offense for “Improper use of turn signal”—the book
contained a citation to § 11-804(d) but provided neither the
statutory language nor any further description of the
offense. Officer Pearce concluded that McDonald did not
need to use his turn signal at the bend in the road and that
he must have improperly used the signal.
  The district court ruled that the anonymous tip would
probably not have been a sufficient ground to stop McDon-
No. 05-3761                                                 3

ald, but that the stop was warranted because Officer Pearce
reasonably believed McDonald’s use of the turn signal was
a violation of state law. The district court also stated in a
footnote that although the statute does not specifically
proscribe McDonald’s use of the turn signal, “it could,
arguably, be so interpreted.” The court denied the motion to
suppress. McDonald then pled guilty, but reserved his right
to appeal the denial of his suppression motion.


                      II. ANALYSIS
  On appeal, McDonald reiterates his argument that the
officers stopped him based on an incorrect interpretation of
the law, and that a mistake of law cannot support probable
cause. We review a district court’s determination of proba-
ble cause de novo and its underlying factual findings for
clear error. United States v. Breit, 

, 728 (7th
Cir. 2005).
  Police can stop an automobile when they have probable
cause to believe that the driver violated even a minor traffic
law. United States v. Muriel, 

, 724 (7th Cir.
2005) (citing Whren v. United States, 

, 810
(1996)). Probable cause exists when an officer reasonably
believes that a driver committed a traffic offense. 

under Terry v. Ohio, 

, 30 (1968), police
may conduct a brief, investigatory traffic stop if they have
reasonable suspicion based on articulable facts that a crime
is about to be or has been committed. United States v.
Baskin, 

, 791 (7th Cir. 2005); United States v.
Wimbush, 

, 949-50 (7th Cir. 2003). A stop and
search can be reasonable even if the defendant did not
actually commit an offense as long as the officer reasonably
believed an offense occurred. United States v. Cashman, 

, 587 (7th Cir. 2000).
  The government maintains that it had probable cause
to stop McDonald because Officer Pearce reasonably be-
4                                                     No. 05-3761

lieved McDonald was violating § 5/11-804(d). We are not
aware of any decision in which an Illinois court has consid-
ered whether a driver who continues to proceed on the same
street after engaging his or her turn signal violates § 5/11-
804(d). We must, therefore, analyze the issue as we expect
the Illinois Supreme Court would if it were deciding the
case. Carter v. Tennant Co., 

, 682 (7th Cir.
2004). According to the Illinois Supreme Court, the primary
rule for statutory construction is to “give effect” to the
intent of the legislature, and the best evidence of that
intent is the plain meaning of the language. Id.; People v.
Powell, 

, 135 (Ill. 2005).
  The statute states that a car’s “electric turn signal
device . . . must be used to indicate an intention to turn,
change lanes or start from a parallel parked position.”
§ 5/11-804(d). The statute also provides that the signal
“must not be flashed on one side only on a parked or
disabled vehicle or flashed as a courtesy or ‘do pass’ signal
to operators of other vehicles approaching from the rear.”

does not state, however, that a driver
must turn onto a different road once the turn signal is
activated.
  The government has not provided any evidence that
§ 5/11-804(d) was intended to address McDonald’s act of
proceeding on the same street after engaging his signal at a
bend in the road. In an analogous case, the Fifth Circuit
interpreted a Texas statute with similar language,1 ruling


1
    The Texas statute states:
     (a) An operator shall use the signal authorized by Section
     545.106 to indicate an intention to turn, change lanes, or
     start from a parked position.
     (b) An operator intending to turn a vehicle right or left shall
     signal continuously for not less than the last 100 feet of
                                                     (continued...)
No. 05-3761                                                      5

that “a plain reading of the Code provisions at issue does
not support the view that having a turn light on without
turning or changing lanes is a violation of Texas law.”
United States v. Miller, 

, 278 (5th Cir. 1998).
The court explained that “[i]t is hard to reconcile the
legislature’s view that these particular uses of signaling had
to be identified as violations if it intended that any other
uses not specifically authorized were to be considered
violations.” 

plain language of the Illinois
statute does not indicate a legislative intent to encompass
McDonald’s use of the turn signal, and the government has
not provided any evidence to show otherwise.
  Officer Pearce was thus mistaken in his belief that
McDonald’s conduct violated the law, and now we must
consider whether the officer’s erroneously held belief
could nonetheless provide probable cause to justify the stop.
Although we have not yet addressed the issue, several other
circuits have determined that even a reasonable mistake of
law cannot support probable cause or reasonable suspicion.
In Miller, the Fifth Circuit determined that because driving
straight with an engaged turn signal is not a violation of
Texas law, “no objective basis for probable cause justified
the stop.” 

. Similarly, the Ninth
Circuit agreed that when a traffic stop is not “objectively
grounded in the governing law,” a mistake of law “cannot
justify the stop under the Fourth Amendment.” United
States v. Lopez-Soto, 

, 1106 (9th Cir. 2000).



1
    (...continued)
       movement of the vehicle before the turn.
      (c) An operator may not light the signals on only one side of
      the vehicle on a parked or disabled vehicle or use the signal
      as a courtesy or ‘do pass’ signal to the operator of another
      vehicle approaching from the rear.
Tex. Transp. Code Ann. § 545.104 (Vernon 1997).
6                                              No. 05-3761

The Tenth and Eleventh Circuits have come to the same
conclusion. See United States v. Tibbetts, 

,
1138 (10th Cir. 2005) (explaining that “failure to under-
stand the law by the very person charged with enforcing it
is not objectively reasonable”); United States v.
Chanthasouxat, 

, 1279 (11th Cir. 2003)
(holding that “a mistake of law cannot provide reasonable
suspicion or probable cause to justify a traffic stop”). The
Eighth Circuit, however, has held to the contrary. See
United States v. Martin, 

, 1001 (8th Cir. 2005)
(stating that objectively reasonable mistakes of either law
or fact can support probable cause).
  We agree with the majority of circuits to have con-
sidered the issue that a police officer’s mistake of law
cannot support probable cause to conduct a stop. Probable
cause only exists when an officer has a “reasonable” belief
that a law has been broken. 

. Law
enforcement officials have a certain degree of leeway to
conduct searches and seizures, but “the flip side of that
leeway is that the legal justification must be objectively
grounded.” 

. An officer cannot have a
reasonable belief that a violation of the law occurred when
the acts to which an officer points as supporting probable
cause are not prohibited by law.
  It makes no difference that an officer holds an under-
standable or “good faith” belief that a law has been broken.
Whether the officer’s conduct was reasonable under
the circumstances is not the proper inquiry. See

. Rather, “the correct
question is whether a mistake of law, no matter how
reasonable or understandable, can provide the objectively
reasonable grounds for providing reasonable suspicion or
probable cause.” 

is that it cannot. A stop
based on a subjective belief that a law has been broken,
when no violation actually occurred, is not objectively
reasonable.
No. 05-3761                                                  7

  By all indications, Officer Pearce genuinely believed
McDonald had violated the law when he did not turn onto
a different road after engaging his signal. As the govern-
ment highlights, the Offense Code Book Officer Pearce
consulted at the time of the stop listed improper use of a
signal as a violation, and it did not provide the statute’s
text. Moreover, no reported case had addressed whether
conduct similar to McDonald’s violated § 5/11-804(d).
  Even though Officer Pearce may have acted in good faith,
there is no good faith exception to the exclusionary rule
when, as here, an officer makes a stop based on a mistake
of law and the defendant is not violating the law.

-80; 

; United States v. Lopez-Valdez, 

,
289 (5th Cir. 1999). As the Ninth Circuit has explained, “To
create an exception here would defeat the purpose of the
exclusionary rule, for it would remove the incentive
for police to make certain that they properly understand the
law that they are entrusted to enforce and obey.” Lopez-

; see also 

(“[I]f officers are allowed to stop vehicles based on their
subjective belief that traffic laws have been violated even
where no such violation has, in fact, occurred, the potential
for abuse of traffic stops as pretext for effecting stops seems
boundless and the costs to privacy rights excessive.”)
  Finally, we note that the mistake of law at issue here
is distinguishable from the circumstances in several cases
cited by the government where an officer stopped a defen-
dant based on a reasonable belief about a fact that later
turned out to be wrong. See Muriel, 

; Cashman,

; United States v. Dexter, 

(7th
Cir. 1999); United States v. Smith, 

(7th Cir.
1996). The government relies on these cases for the proposi-
tion that the relevant inquiry for probable cause or reason-
able suspicion was not whether the defendant was actually
guilty of violating the law, but whether the police had a
8                                                No. 05-3761

reasonable belief that the defendant was committing an
offense. But the government’s reliance on these cases is
misplaced. In each of these cases, the officers relied on
actual state laws when deciding to stop the defendants.
When an officer makes a stop based on a mistake of fact, we
ask only whether the mistake was reasonable. In contrast
to the circumstances in the “mistake of fact” line of cases on
which the government relies, even if McDonald acted
exactly as Officer Pearce believed, his actions were not a
violation of any Illinois state traffic law.
  Because the officers here did not have probable cause
to stop McDonald, the district court should have granted his
motion to suppress.


                   III. CONCLUSION
  Accordingly, the district court’s decision is REVERSED and
we REMAND for further proceedings consistent with this
opinion.
No. 05-3761                                          9

A true Copy:
      Teste:

                    ________________________________
                    Clerk of the United States Court of
                      Appeals for the Seventh Circuit




               USCA-02-C-0072—7-17-06