(concurring).
Although I agree that appellant’s conviction should be vacated, I have serious reservations about the majority’s approach to that result. The majority unnecessarily addresses .the constitutional validity of anticipatory search warrants and, having done that, resolves the issue incorrectly.
*18I begin by describing the areas in which my views are most similar to those of the majority. We both agree that the warrant in this case was utterly unsupported by probable cause. I find, however, that the warrant was tainted by information too stale to carry the crisp reliability necessary to find probable cause. While the majority contentedly dismisses this aspect of the case, ante at 14 n. 6, I believe that it provides for the proper resolution of this appeal.
As the majority eloquently states, “In 1988, Houston police breathed life into a moribund child pornography investigation by giving federal postal inspectors a customer list unearthed during a 1975 probe of a suspected pornography distributor.” Ante at 9. The activity unearthed by the moribund investigation — appellant ordered two films from a child pornography dealer — occurred in 1974. In 1990, postal inspectors conducted a sting which lured appellant to buy forbidden films, and applied for a warrant to search his home for those and other materials. The 1990 operation and warrant application were based, thus, on appellant’s activities which occurred sixteen years before.
In this circuit, we do not measure staleness merely on the basis of the maturity of the information. United States v. Bucuvalas, 970 F.2d 937, 940 (1st Cir.1992), cert. denied, — U.S. -, 113 S.Ct. 1382, 122 L.Ed.2d 758 (1993). Other factors include 1) whether the criminal activity is ongoing or discrete; 2) whether the' criminal is entrenched or nomadic; 3) whether the items to be seized are long-lasting or perishable; and 4) whether the premises to be searched are a secure operating base or a mere criminal forum. Id. The application of these factors to the facts of the present case, some not fully detailed in the majority opinion, discloses the stagnant heart of this ease.
First, the statute that appellant is accused of violating, 18 U.S.C. § 2252(a)(2), prohibits the receipt of child pornography through interstate commerce or mail. The evidence in the record of this case shows that appellant only engaged in this activity twice, on occasions' separated by sixteen years. The activity clearly cannot be described as ongoing. This conclusion is buttressed by the fact that when appellant placed the first order, in 1974, the receipt of child pornography through the mail was not prohibited. An early version of § 2252 did not appear until 1978, with a substantial amendment occurring in 1984, ten years after appellant’s first order. Thus, appellant’s first order was not even illegal. This is a point that must be emphasized. There was no ongoing illegal activity in this case, because appellant acted illegally only once, when the government induced him to do so in a sting operation. In other words, appellant’s recent purchase did not update the 1974 purchase, because those earlier activities are not comparable in terms of violation of the law.
Appellant’s nomadic nature also negates the ongoing reliability of his 1974 activity. At that time, appellant lived in Newton, Massachusetts. Appellant later moved to Framingham, Massachusetts, and yet again to another address in Framingham. Appellant lived at his final residence with his mother and brother, sharing a room with his sibling. The affidavit contained no information even tending to show that appellant retained the 1974 materials through these relocations, or that his coresidents tolerated the presence of prurient material in the shared premises.
I concede that the affidavit showed the ongoing utility of child pornography to collectors and pedophiles, discussing how such individuals keep their dross for long periods of time. Standing alone, however, this information does not justify the conclusion that appellant kept the materials throughout sixteen years and two relocations. The affidavit did not. define collector and pedophile, or characterize appellant as a member of either class. See United States v. Weber, 923 F.2d 1338, 1345 (9th Cir.1990) (concerning similar affidavit, the court noted “the affidavit does not say how many magazines or pictures one must buy in order to be defined as a ‘collector’ ”). As such, the affidavit is inconclusive as to the ongoing utility of the materials to appellant, especially in light of his various relocations and the long passage of time. Additionally, it cannot be presumed automatically that appellant would keep material which was illegal as a result of subsequent *19legislation, once such a law went into effect in 1978.
Finally, there is no showing that appellant’s address was a secure base. The affidavit did not adduce that appellant kept a cache of child pornography there, and appellant’s relocations weaken the existence of this possibility. The affidavit merely established that the address was appellant’s home, which he shared with his mother and brother. Again, the fact that he shared his premises with nonparticipants in the criminal enterprise is a weakening point in terms of the presence of contraband at that location.
Based on these factors, I find it easy to conclude that the information pertaining to appellant’s 1974 materials could not support a probable cause finding in this case. Yet, the stagnant information formed the heart of the inspector’s affidavit and was the only basis for the attenuated inference that appellant amassed child pornography at his home. Without it, the sting operation and the search warrant fall. This is as far as we should go, proceeding directly to quash the conviction. It is unnecessary to go further into constitutional speculation.
The majority proceeds, however, to answer . unnecessarily a wholly novel question for this circuit: whether the anticipatory search warrant in this case was constitutional. Worse yet, it issues a blanket license allowing its proliferation into common use.
For the majority to do so is an imprudent exercise of our judicial power. It is axiomatic that we avoid constitutional rulings unless they are strictly necessary. El Día, Inc. v. Hernández Colón, 963 F.2d 488, 494 (1st Cir.1992) (citing Alabama State Federation of Labor v. McAdory, 325 U.S. 450, 461, 65 S.Ct. 1384, 1389, 89 L.Ed. 1725 (1945); Ashwander v. Tennessee Valley Auth., 297 U.S. 288, 346-55, 56 S.Ct. 466, 482-87, 80 L.Ed. 688 (1936) (Brandeis, J., concurring); Aggarwal v. Ponce School of Medicine, 745 F.2d 723, 726 (1st Cir.1984)). The long standing rationale for this rule is to avoid issuing advisory opinions. United States v. Hastings, 296 U.S. 188, 193, 56 S.Ct. 218, 220, 80 L.Ed. 148 (1935). Because the search warrant in this case was utterly unsupported by probable cause, addressing the constitutionality of anticipatory search warrants amounts to such an impermissible advisory opinion.
To complicate matters, the majority elects the wrong side of this unnecessary constitutional issue, choosing a problematic and erroneous- result in this ease. Anticipatory search warrants are violative of the Fourth Amendment, which plainly states that' “no Warrants shall' issue, but upon probable cause.” Probable cause must exist to believe at the time of issuance that the contraband is in the place to be searched. Steagald v. United States, 451 U.S. 204, 213, 101 S.Ct. 1642, 1648, 68 L.Ed.2d 38 (1981) (warrants issue upon showing of “probable cause to believe that the legitimate object of a search is located in a particular place”) (emphasis added); United States v. Salvucci, 599 F.2d 1094, 1096 (1st Cir.1979) (“the Fourth Amendment requires that the supporting affidavits set forth facts sufficient to allow a neutral magistrate to reasonably conclude that the property sought is located on the premises to be searched at the time the warrant issues”) (emphasis added), rev’d on other grounds, 448 U.S. 83, 100 S.Ct. 2547, 65 L.Ed.2d 619 (1980); see also Sgro v. United States, 287 U.S. 206, 208, 53 S.Ct. 138, 139, 77. L.Ed. 260 (1932) (“the proof [supporting probable cause] must be of facts so closely related to the time of the issue of the warrant as to justify a finding of probable cause at that time”).
The requirement of contemporaneous probable cause flows from the interests animating the Fourth Amendment. One of the principle evils which that provision prevents is vesting law enforcement officers with any discretion as to whether or not the conditions of the warrant have been complied with. This is precisely what anticipatory warrants permit in deviating irom the contemporaneous probable cause standard.
It is well established that “[t]he security of one’s privacy against arbitrary intrusion by the police — which is at the core of the Fourth Amendment — is basic to a free society.” Coolidge v. New Hampshire, 403 U.S. 443, 453, 91 S.Ct. 2022, 2031, 29 L.Ed.2d 564 (1971) (quoting Wolf v. Colorado, 338 U.S. 25, 27, 69 S.Ct. 1359, 1361, 93 L.Ed. 1782 (1949)). *20Accordingly, the Fourth Amendment places very stringent limits on officers invading an individual’s privacy. “‘The proceeding by search warrant is a drastic one,’ and must by carefully circumscribed so as to prevent unauthorized invasions of ‘the sanctity of a mail’s home and the privacies of life.’ ” Berger v. New York, 388 U.S. 41, 58, 87 S.Ct. 1873, 1883, 18 L.Ed.2d 1040 (1967).
The Fourth Amendment forbids general warrants to prevent law enforcement officers from rummaging through an individual’s belongings at will. E.g., Andresen v. Maryland, 427 U.S. 463, 480, 96 S.Ct. 2737, 2748, 49 L.Ed.2d 627 (1976) (quoting Coolidge, 403 U.S. at 467, 91 S.Ct. at 2038). The requirement of a particular description “‘makes general searches ... impossible and prevents the seizure of one thing under a warrant describing another. As to what is to be taken, nothing is left to the discretion of the officer executing the warrant.’ ” Id. (quoting Stanford v. Texas, 379 U.S. 476, 485, 85 S.Ct. 506, 511, 13 L.Ed.2d 431 (1965), itself quoting Marron v. United States, 275 U.S. 192, 196, 48 S.Ct. 74, 76, 72 L.Ed. 231 (1927)). Thus, a warrant authorizing a search for obscene. publications was deficient because it “merely repeated the language of the statute and the complaints, specified no publications, and left to the individual judgment of each of the many police officers involved in the selection of such magazines as in his view constituted ‘obscene ... publications.’ ” Marcus v. Search Warrant, 367 U.S. 717, 732, 81 S.Ct. 1708, 1716, 6 L.Ed.2d 1127 (1961).
Furthermore, the Fourth Amendment requires that the probable cause determination be made by a neutral and detached magistrate, rather than by the oíñcers conducting the search. It has long been established that
the point of the Fourth Amendment, which often is not grasped by zealous officers, is not that it denies law enforcement the support of the usual inferences which reasonable men draw from evidence. Its protection consists in requiring that those inferences be drawn by a neutral and detached magistrate instead of being judged by the officer engaged in the often competitive enterprise of ferreting out crime.
Johnson v. United States, 333 U.S. 10, 13-14, 68 S.Ct. 367, 369, 92 L.Ed. 436 (1948). Otherwise, the Fourth Amendment would be a “nullity” and homes would be “secure only in the discretion of police officers.” Id. at 14, 68 S.Ct. at 369.
It is thus clear that the Fourth Amendment is concerned with insulating the citizenry from the whims of law enforcement officers. Plainly and simply, the use of anticipatory search warrants erodes this insulation. When an officer is given an anticipatory search warrant, the magistrate essentially instructs the officer as follows: When the following conditions occur, probable cause to conduct a search will arise. The officer is then left to determine unilaterally whether, when, and how the conditions occur which give rise to probable cause.
Law enforcement officers should not be the ones, absent exigent circumstances, that engage in the sensitive balancing required to weigh the merits of probable cause in a given case because they are not neutral parties to the determination of that • crucial inquiry. The majority recognizes the need to limit the officers’ discretion in executing an anticipatory warrant, but nonetheless foists upon the officers a determination that is quite sensitive in a constitutional sense. An anticipatory warrant can only be executed when four threads come together to form a coherent nexus: the criminal act, the evidence to be seized, the place to be searched, and the “temporal dimension.” Ante at 13. The officers have virtually unfettered discretion to determine when this “temporal dimension” has been fulfilled, with no input from a neutral and detached judicial officer.
The majority also recognizes that “[w]hen issuing anticipatory warrants, magistrates must rely to a large extent on the expertise of federal agents as to the certainty that the triggering event will occur.” Ante at 16. Because the majority finds that probability is the touchstone of probable cause, ante at 12, this fact demonstrates the great amount of discretion delegated to law enforcement officers in the anticipatory search warrant context. Law enforcement officers put together the probability that gives rise to probable cause, and then determine when the eventu*21ality occurs. In other words, the officers are in control of the entire warrant process, shaping the probable cause determination from start to finish. Such an unfettered and judicially uncontrolled intrusion into an individual’s privacy interest is precisely what the Fourth Amendment was designed to prevent.
Incredibly, given the majority’s resolution of the issue, no government interest weighed heavily in favor of the use of anticipatory search warrants. See New Jersey v. TLO, 469 U.S. 325, 337, 105 S.Ct. 733, 740, 83 L.Ed.2d 720 (1985) (balancing “the individual’s legitimate expectations of privacy and personal security” with “the government need for effective methods to deal with breaches of public order” in passing on the validity of a class of searches).
An officer “engaged in the often competitive enterprise of ferreting out crime,” Johnson, 333 U.S. at 14, 68 S.Ct. at 369, has two options in cases such as this one. Once the controlled delivery of contraband is complete, he may apply for a search warrant to the appropriate magistrate. Alternatively, if an exigency should arise in the course of the controlled delivery requiring immediate action, the officer is authorized to conduct a warrantless search pursuant to the well-known exigent circumstances exception to the warrant requirement. In short, there is no legitimate need for such a novel erosion of the Fourth Amendment as is promoted by anticipatory search warrants.
The majority’s analogy to warrants for wiretapping, ante at 11 n. 3, is misapplied. When authorizing a wiretap, a magistrate must observe “precise and discriminate” procedures specific to wiretaps. Katz v. United States, 389 U.S. 347, 355, 88 S.Ct. 507, 513, 19 L.Ed.2d 576 (1967) (quoting Berger, 388 U.S. at 57, 87 S.Ct. at 1882). For example, the magistrate must identify the telephone number to be tapped and the conversations to be seized. United States v. Donovan, 429 U.S. 413, 97 S.Ct. 658, 50 L.Ed.2d 652 (1977). Probable cause must be fully in place before the wiretap is authorized. These safeguards ensure that “ ‘no greater invasion of privacy [is] permitted than [is] necessary under the circumstances.’ ” Katz, 389 U.S. at 355, 88 S.Ct. at 513 (quoting Berger, 388 U.S. at 57, 87 S.Ct. at 1882). They thus afford “ ‘similar protections to those ... of conventional warrants.’ ” Id.
As discussed above, anticipatory search warrants, in addition to lacking the basic protections of conventional warrants, are simply unnecessary to any legitimate law enforcement need. Normal search warrants and the exigent circumstances exception adequately address whatever need may arise in a controlled delivery. As such, allowing the government to employ a new technique with which to invade an individual’s privacy interest is completely unwarranted (no pun intended).