227 F.3d 1038 (7th Cir. 2000)
United States of America, Plaintiff-Appellee,v.Zoila Melgar, Defendant-Appellant.
No. 99-3322
In the  United States Court of Appeals  For the Seventh Circuit
Argued February 23, 2000Decided September 19, 2000

Appeal from the United States District Court  for the Western District of Wisconsin.  No. 99-CR-13-C--Barbara B. Crabb, Judge.
Before Flaum, Chief Judge, Kanne and Diane P. Wood,  Circuit Judges.
Diane P. Wood, Circuit Judge.


1
Zoila Melgar  pleaded guilty to one count of conspiracy to  commit bank fraud and interstate transportation  of counterfeit securities, conditioned on her  right to challenge and now to appeal from the  district court's denial of her motion to suppress  evidence found inside a purse. The district court  relied on the "inevitable discovery" doctrine to  support its ruling, but we conclude that there is  a more straightforward way to reach the same  result. The purse was discovered by the police  during the course of a search to which the renter  of the hotel room had validly consented, and  under the circumstances the police were permitted  to investigate the contents of the purse as well.  We therefore affirm the judgment of the district  court, but on different grounds.


2
* On January 29, 1999, officers of the Madison,  Wisconsin, police department arrested four men on  charges of passing counterfeit dividend checks  supposedly issued by the Johnson Controls  Corporation. A search of their car turned up a  receipt showing that a Rita Velasquez had rented  Room 136 at a local Holiday Inn. Officers Louis  Geblar and Bruce Frey, following up on that lead,  drove to the hotel and went to the room in  question. Joel Mejia responded to their knock on  the door. He gave them permission to enter the  room, where they found three other people: Celenia Mejia, Oscar Barrientos, and Jose  Vasquez. Only Joel Mejia was fluent in English,  and so the officers first asked him about the  counterfeiting scheme, and then had him serve as  a translator for the others. Geblar asked  everyone present for consent to search their  wallets or purses, and everyone agreed.


3
After this exchange, three more women arrived  at the room: Rita Velasquez herself, Marcella  Hernandez, and the defendant Zoila Melgar. Geblar  asked Velasquez to step into the hall, where he  searched her purse and jacket, found a  counterfeit check, and arrested her. (Velasquez  told him that the check was a joke, but he  obviously found that story implausible.) On a  more serious note, Velasquez also told Geblar  that she saw Melgar give Hernandez a large number  of checks, and that Hernandez had placed these  checks in her purse.


4
Geblar returned to the room and next summoned  Hernandez into the hall with him. There he  searched her purse, but he found nothing  incriminating in it. When he asked Velasquez to  offer an explanation, she indicated that the  checks were in a second purse Hernandez owned (a  black one), that was still in the room. Geblar  held up that purse and asked everyone whose purse  it was, but no one claimed ownership. He then  opened it and found an envelope with Hernandez's  name on it that contained fake Johnson Control  checks. At that point, he arrested Hernandez.


5
Once again, Geblar then asked Velasquez to  accompany him to the hall. This time he asked for  her permission to search the room. His request  was a general one; he did not specifically ask  her if the police could search particular closed  containers within the room, nor did he ask her  which of the numerous people then in the room  were actually staying there. Velasquez gave her  permission, which she signified both orally and  by signing a scrap of paper (since lost) on which  Geblar had scribbled out a consent form. At that  point, the officers arrested and handcuffed  everyone who had not already been arrested  (including Melgar) and sent them to the station  house.


6
After they all departed, the officers began  their search of the room. Between the mattress  and box springs of one of the beds, Frey found a  floral purse that had no personalized markings on  the outside. He opened it, and found inside an  identification form that bore Melgar's photograph  and the name "Diana Lopez." He also found a  counterfeit Johnson Controls check payable to  Diana Lopez. It is this evidence that  incriminated Melgar, and it is the district  court's refusal to suppress this evidence on the  ground that it was obtained in violation of the  Fourth Amendment that Melgar challenges in this  appeal.

II

7
Melgar reasons that the evidence of the  contents of the purse should have been suppressed  because the police never obtained permission from  anyone to search that particular closed container  in Room 136. The police should have understood  that the purse did not necessarily belong to  Velasquez because there were several women in the  room. Furthermore, she continues, the amount of  luggage and other belongings scattered around  made it obvious that Velasquez was not the sole  occupant. Melgar concedes that Velasquez had at  least apparent authority to authorize the search  of the room itself, but she argues that this  authority did not (either actually or apparently)  extend to closed containers within the room. She  also suggests that because the police had already  matched up the other purses they had seen with  the other women, they should have assumed that  the purse underneath the mattress was Melgar's.


8
The district court saw enough possible merit in  Melgar's arguments that it chose not to rely on  consent in its ruling on the motion. Instead, it  turned to an argument that had not been raised  before the magistrate judge, upon whose report  and recommendation the district court was  relying. That argument was "inevitable  discovery": had the police refrained from  searching the floral purse then and there, out of  concern for the lack of a warrant justifying such  a search, they would simply have secured the  room, obtained a warrant, and then opened the  purse and obtained exactly the same damning  materials they did. On appeal, the government  raises another argument that it failed to make  before the magistrate judge, namely, that the  purse might have been subject to a valid search  incident to an arrest.


9
Our cases, however, indicate that arguments not  made before a magistrate judge are normally  waived. See, e.g., Divane v. Krull Electric Co.,  194 F.3d 845, 849 (7th Cir. 1999). It is also  true that we have said that waiver is a flexible  doctrine, see Old Ben Coal Co. v. Director,  Office of Workers' Compensation Programs, 62 F.3d  1003, 1007 (7th Cir. 1995), but there are good  reasons for the rule that district courts should  not consider arguments not raised initially  before the magistrate judge, even though their  review in cases governed by 28 U.S.C. sec.  636(b)(1) is de novo. Failure to raise arguments  will often mean that facts relevant to their  resolution will not have been developed; one of  the parties may be prejudiced by the untimely  introduction of an argument (which Melgar argues  is the case here). Additionally, a willingness to  consider new arguments at the district court  level would undercut the rule that the findings  in a magistrate judge's report and recommendation  are taken as established unless the party files  objections to them. We need not decide here,  however, whether there might be exceptions to  this rule in unusual cases, or if this was such  a case. The ground actually presented to the  magistrate judge was consent. The government did  not abandon that argument either before the  district court or this court, and it is  sufficient to support the district court's  ruling, as we now explain.


10
The probable cause and warrant requirements of  the Fourth Amendment are not applicable where a  party consents to a search, Schneckloth v.  Bustamonte, 412 U.S. 218 (1973), where a third  party with common control over the searched  premises consents, Florida v. Jimeno,  500 U.S.  248 (1991), or where an individual with apparent  authority to consent does so, Illinois v.  Rodriguez, 497 U.S. 177 (1990). Here, there is no  dispute that Velasquez was the person who had  rented the room, that she gave her consent for a  search, and that she had authority (or at least  apparent authority) to do so. Generally, consent  to search a space includes consent to search  containers within that space where a reasonable  officer would construe the consent to extend to  the container. Jimeno, 500 U.S. at 251; see also  Wyoming v. Houghton, 526 U.S. 295, 302 (1999)  (applying this rule to searches of a container  within an automobile, if the container is of a  type that might conceal the object of the  search); United States v. Ross, 456 U.S. 798  (1982) (same).


11
Melgar responds that there is an exception for  closed containers that the police have no reason  to believe are under the control of the person  who agreed to the search. She relies principally  on our decision in United States v. Rodriguez,  888 F.2d 519 (7th Cir. 1989), in which we held  that a spouse's consent to search a room in a  union hall where her husband was sleeping did not  extend to her husband's briefcase, which had the  word "Mike" on the outside. Id. at 524. The  opinion reasoned that consent to search premises  cannot always extend to every closed container  within them, because such a rule would imply that  consent to search the United Airlines baggage  facility at O'Hare Airport would justify  searching everyone's luggage--a proposition we  were not willing to endorse. On the other hand,  the government responds, in United States v.  Saadeh, 61 F.3d 510 (7th Cir. 1995), this court  upheld a workplace search in which the police  made it clear they were looking for drugs, the  employer consented to the search of an entire  facility, and the police found drugs in a closed  toolbox and desk. Id. at 516-19. Saadeh,  according to the government, controls this case  and demonstrates that the police were entitled to  search the contents of the floral purse.


12
In our view, neither Rodriguez nor Saadeh is  directly on point, but taken together they can  guide us to the correct result. In a sense, the  real question for closed container searches is  which way the risk of uncertainty should run. Is  such a search permissible only if the police have  positive knowledge that the closed container is  also under the authority of the person who  originally consented to the search (Melgar's  view), or is it permissible if the police do not  have reliable information that the container is  not under the authorizer's control. We are not  aware of any case that has taken the strict view  represented by the first of these possibilities.  With respect to the search of the briefcase in  Rodriguez, the police had positive information  that it did not belong to his spouse (the name  label on the outside). The same is true for the  suitcases in a baggage facility, which must have  on the outside an identification tag with the  passenger's name and address. No reasonable  police officer, having obtained the airline's  permission to search the facility, could think  that the airline is also authorized to speak for  each individual passenger whose luggage is stored  there. See also United States v. Fultz, 146 F.3d  1102, 1106 (9th Cir. 1998) (property owner made  clear that the boxes were not hers); United  States v. Welch, 4 F.3d 761, 765 (9th Cir. 1993)  (purse clearly did not belong to driver).


13
Here, the police had no reason to know that the  floral purse they found under the mattress did  not belong to Velasquez. They knew that the room  had been rented to Velasquez; they knew that at  least one of the women, Hernandez, had two  purses; and there were no exterior markings on  the purse that should have alerted them to the  fact that it belonged to another person. Coupling  those facts with the fact that Velasquez knew  that they were searching for evidence of  counterfeit dividend checks, which could easily  fit inside the purse, we conclude that the scope  of Velasquez's consent encompassed their right to  look into this container.


14
A contrary rule would impose an impossible  burden on the police. It would mean that they  could never search closed containers within a  dwelling (including hotel rooms) without asking  the person whose consent is being given ex ante  about every item they might encounter. We note  that there is no possibility of such a rule for  automobile searches, because the Supreme Court  has already authorized this type of container  search in that context. See Ross, supra;  Houghton, supra. Our conclusion here rests in  part on the discussion in Houghton that indicates  that the container rule rests on general  principles of Fourth Amendment law that do not  depend on the special attributes of automobile  searches. See 526 U.S. at 302.

III

15
Because the police had no reason to believe  that Velasquez could not consent to the search of  the floral purse, and because (as Melgar  conceded) Velasquez gave her consent to a  complete search of Room 136, we hold that the  search of the purse did not violate the Fourth  Amendment and that the district court correctly  declined to grant Melgar's motion to suppress.  The judgment of the district court is Affirmed

