MURNAGHAN, Circuit Judge:
A jury convicted Lawrence David Ramapuram under a one count indictment for violating 18 U.S.C. § 842(h).1 The charge arose from a theft from a cemetery bunker of fifty pounds of dynamite. The principal issue raised on appeal is whether the district court erred in overruling Ramapuram’s motion to suppress evidence allegedly obtained in violation of the Fourth Amendment prohibition of unreasonable searches and seizures.2 Ramapuram also seeks reversal on the grounds that the district court erred in its instructions to the jury and in concluding that it had jurisdiction over the case.
I.
A.
Ramapuram, who was seventeen years old at the time,3 together with a sixteen [1151]*1151year old associate, Fisher, whose assistance Ramapuram sought and obtained, broke into the concrete cemetery bunker and removed the dynamite (approximately 100 sticks) on December 16, 1975. Cemetery employees discovered the theft a week later, on December 23,1975, and reported the same to the Bureau of Alcohol, Tobacco and Firearms on December 24, 1975. Agent MeMonagle of the ATF began an immediate investigation. The Maryland State Police also investigated the theft.
Recovery of most of the dynamite and Ramapuram’s subsequent arrest resulted from a warrantless search and seizure which occurred under the following circumstances. Agent MeMonagle received a report on New Year’s Eve at or about 3:30 p. m. from a state police detective, Tenny, that Ramapuram and Fisher were responsible for the theft. Tenny received his information from his son, an acquaintance of Ramapuram and of Fisher, who was present near the cemetery on the night of the theft and who, in fact, had observed, with others, Ramapuram and Fisher load the dynamite into Ramapuram’s automobile. Detective Tenny also advised MeMonagle that, according to the former’s son, Ramapuram had expressed the intention to blow up certain public buildings. Later, on December 31, 1975, MeMonagle learned that Fisher was in the custody of the Maryland State Police. MeMonagle proceeded to the location where Fisher was being held and interviewed him. Sometime between 5:00 p. m. and 6:00 p. m. on the same day, December 31, 1975, Fisher told MeMonagle that the dynamite was in the trunk of a Chevrolet automobile which was parked in a field on a farm located in Baltimore County, Maryland, and owned by Ramapuram’s father, a medical practitioner. MeMonagle, accompanied by another ATF agent and two state police troopers,4 first went to the Ramapuram home to talk to Ramapuram’s father, who, however, was not there. They then proceeded directly to the farm, arriving at or about 6:30 p. m.5
It was raining and dark as the vehicle containing the agents and troopers left the public road and entered the farm along a narrow private road. The vehicle advanced approximately two hundred yards from the public road whereupon it became mired in the mud. The district court found that the members of McMonagle’s party:
left their car and approached a Chevrolet automobile parked in an open area near a fenced paddock at a distance of 150 to 200 feet from the main road.
The Agent observed that the car appeared to have been abandoned, that the license plates had expired, the doors were unlocked, and the trunk lock had been removed. The Agent opened the trunk of the car and found that it contained 88 sticks of dynamite which according to the ‘date/shift code’ was [sic] part of the dynamite stolen from Woodlawn Cemetery. The officers removed the dynamite from the premises and thereafter turned it over to military personnel to be taken [1152]*1152to Edgewood Arsenal. The Chevrolet from which the dynamite was removed was titled in the name of the defendant’s father but had been owned for the use of the defendant. Patarama Farm on which the Chevrolet was parked was owned by the defendant’s father and the father’s former wife. Neither the defendant nor his father lived on the farm but both had access to it and used it on occasion.
Dr. Ramapuram testified at the suppression hearing as well as at trial that the fifteen acre farm was used primarily to board and ride horses, by members of the Ramapuram family and others. At trial, he testified that the lone residence located on the farm was under lease to unspecified tenants. The 1964 Chevrolet automobile from which the dynamite was seized was described by the district court based on photos which are a part of the record as a “junker;” it was not the automobile driven by Ramapuram on the night of the theft.6 Dr. Ramapuram testified that although the “junker” was titled in his name it had been held for use by and used by his son. Dr. Ramapuram could not remember when the “junker” was taken out of service and left on the farm. As the district court found, the “junker” had no current state license tags, the trunk lock assembly had been removed and the doors were unlocked.
It is undisputed that no search warrant was obtained and, indeed, that no effort whatsoever was made to determine the availability of a judge or magistrate to whom application could be made for such warrant. Likewise, it is apparently undisputed, as counsel for Ramapuram conceded at argument, that ample probable cause existed to support a search warrant for the “junker” after the McMonagle-Fisher interview.
At trial, aerial photographs of the pertinent area of the farm, close-up photographs of the “junker” and of the dynamite in the trunk, and McMonagle’s testimony concerning the seizure were admitted. Additionally, findings from a chemical analysis of the recovered dynamite and testimony concerning the controlled detonation of the dynamite were admitted.
Over government opposition, the district court concluded that (a) Ramapuram had standing to raise the Fourth Amendment contention; and (b) Ramapuram possessed a reasonable expectation of privacy as to matters stored in the trunk of the “junker”. The district court, nevertheless, concluded that the warrantless search of the trunk of the “junker” was justified by exigent circumstances. The district court relied on several cases involving warrantless searches or seizures of explosives and weapons in varying circumstances.7 There are, however, cases concluding that prosecutorial assertions of exigency were insufficient to excuse compliance with the warrant requirement.8
Which of the two lines of cases to follow is a far from easy question to resolve. Nothing in the record sufficiently established a high volatility and grave potential of explosion for the dynamite abstracted from the cemetery bunker. Exigency is urged on the idea that, with approximately 100 sticks of dynamite actually in Ramapu[1153]*1153ram’s possession, his threats to blow up public buildings made the urgency of a concentrated manhunt very great. However, if it could be established that the dynamite was in the “junker” and, therefore, shielded from Ramapuram by the presence of law enforcement officers, the exigency of the search for him was reduced and might proceed more routinely.
In view of the existence of a more direct and established ground which validates the warrantless search and seizure, we expressly refrain from deciding whether such “exigency once removed” sufficed to render unnecessary a warrant in the present case. We note that United States v. McKinney, 477 F.2d 1184, 1186 (D.C. Cir. 1973), involved “a sawed-off shotgun, an ominous threat in and [of] itself.” However, in the present case, the dynamite’s risk is not simply inherent, but would depend on the particular destructive intent of Ramapuram. Cf. Mincey v. Arizona, 437 U.S. 385, 394, 98 S.Ct. 2408, 2415, 57 L.Ed.2d 290 (1978) (“We decline to hold that the seriousness of the offense under investigation itself creates exigent circumstances of the kind that under the Fourth Amendment justify a warrantless search.”).
The alternate ground is our conclusion that Ramapuram had no reasonable expectation of privacy. While warrantless searches and seizures are presumptively unreasonable under the Fourth Amendment, Katz v. United States, 389 U.S. 347, 357, 88 S.Ct. 507, 514, 19 L.Ed.2d 576 (1967), the thrust of the Fourth Amendment simply does not extend to locations lacking a foundation for reasonably expecting that the materials will be accorded privacy. Exploration by the government although without a warrant of non-private places does not compel the suppression of evidence so obtained. Rakas v. Illinois, 439 U.S. 128, 143, 99 S.Ct. 421, 430, 58 L.Ed.2d 387 (1978); id. at 150-56, 99 S.Ct. at 434 (Powell, J., concurring); Rawlings v. Kentucky, - U.S. —, 100 S.Ct. 2556, 65 L.Ed.2d 633 (1980).
B.
In Patler v. Slayton, 503 F.2d 472, 477-78 (4th Cir. 1974), a federal habeas corpus attack on a state murder conviction,9 one issue raised on appeal was the alleged impropriety under the Fourth Amendment of a search of a pasture located on a farm owned by Patler’s father-in-law and the seizure therefrom of several spent bullets and shell casings matching the murder weapon. The district court held that in the absence of a reasonable expectation of privacy Patler had no standing and, therefore, could not raise the Fourth Amendment issue on federal habeas corpus. On appeal, this court disagreed with the lower court’s determination that Patler lacked standing, relying on United States v. Cobb, 432 F.2d 716 (4th Cir. 1970), and Brown v. United States, 411 U.S. 223, 93 S.Ct. 1565, 36 L.Ed.2d 208 (1973). We held, however, that Patler “failed to demonstrate a reasonable expectation of privacy in the property actually searched” and that, therefore, no violation of the Fourth Amendment had been made out. Subsequent teachings from the Supreme Court have clarified that in Patler both the lack-of-standing approach of the district court and the no-reasonable-expectation approach of the court of appeals were correct, and both sufficed as reasons for a denial of habeas corpus. This is so because, under Rakas v. Illinois, 439 U.S. 128, 99 S.Ct. 421, 58 L.Ed.2d 387 (1978), and Rawlings v. Kentucky,-U.S.-, 100 S.Ct. 2556, 65 L.Ed.2d 633 (1980), “the two inquiries [of standing and of substantive Fourth Amendment protection] merge into one: whether governmental officials violated any legitimate expectation of privacy . . . . ” Rawlings v. Kentucky, - U.S. at -, 100 S.Ct. at 2562. The Rawlings court might well have been speaking of Patler in stating “Prior to Rakas, petitioner might have been given ‘standing’ in such a [1154]*1154case to challenge a ‘search’ that netted [the evidence] but probably would have lost his claim on the merits.” Id. See United States v. Jackson, 585 F.2d 653, 660 (4th Cir. 1978) (“[Without an [expectation of privacy] [defendant] had neither standing nor a right to complaint.”).
As we perceive the relevant principles, it devolves upon one seeking suppression of incriminating evidence to establish as a threshhold matter the existence of a reasonable expectation of privacy in the area searched. United States v. Torch, 609 F.2d 1088, 1091 (4th Cir. 1979) (“The test for whether a person may have evidence obtained in an unlawful search and seizure suppressed is whether the person had ‘a reasonable expectation of freedom from government intrusion in the invaded place’.”). In many cases such a showing will be readily achieved. Arkansas v. Sanders, 442 U.S. 753, 762, 99 S.Ct. 2586, 2592, 61 L.Ed.2d 235 (1979) (“[L]uggage is a common repository for one’s personal effects, and therefore is inevitably associated with the expectation of privacy.”); United States v. Presler, 610 F.2d 1206, 1213-14 (4th Cir. 1979) (“The very act of locking them and retaining either the key or the combination to the locks on the two briefcases was an effective expression of the defendant’s expectation of privacy.”). In other cases, it will be all but impossible to demonstrate a reasonable expectation of privacy, even where the movant is the owner of the property searched. United States v. Dall, 608 F.2d 910, 914 (1st Cir. 1979), cert. denied, 445 U.S. 918, 100 S.Ct. 1280, 63 L.Ed.2d 603 (1980) (“Ownership alone is not enough to establish a reasonable and legitimate expectation of privacy. Ownership is relevant to the inquiry ..., but the total circumstances determine whether the one challenging the search has a reasonable and legitimate expectation of privacy in the locus of the search.”); United States v. Rios, 611 F.2d 1335, 1345 (10th Cir. 1979).
“What is a reasonable expectation of privacy is by definition related to time, place and circumstance.” United States v. Vicknair, 610 F.2d 372, 380 (5th Cir. 1980). Considerable guidance is afforded by several Supreme Court cases. In short:
the application of the Fourth Amendment depends on whether the person invoking its protection can claim a “justifiable,” a “reasonable,” or a “legitimate expectation of privacy” that has been invaded by government action. E. g., Rakas v. Illinois, 439 U.S. 128, 143, and n.12, 99 S.Ct. 421, 430 & n.12, 58 L.Ed.2d 387 (1978); id., at 150, 151, 99 S.Ct. at 434 (concurring opinion); id., at 164, 99 S.Ct. at 441 (dissenting opinion); United States v. Chadwick, 433 U.S. 1, 7, 97 S.Ct. 2476, 2481, 53 L.Ed.2d 538 (1977); United States v. Miller, 425 U.S. 435, 442, 96 S.Ct. 1619, 1623, 48 L.Ed.2d 71 (1976); United States v. Dionisio, 410 U.S. 1, 14, 93 S.Ct. 764, 771, 35 L.Ed.2d 67 (1973); Couch v. United States, 409 U.S. 322, 335-336, 93 S.Ct. 611, 619, 34 L.Ed.2d 548 (1973); United States v. White, 401 U.S. 745, 753, 91 S.Ct. 1122, 1126, 28 L.Ed.2d 453 (1971) (plurality opinion); Mancusi v. DeForte, 392 U.S. 364, 368, 88 S.Ct. 2120, 2123, 20 L.Ed.2d 1154 (1968); Terry v. Ohio, 392 U.S. 1, 9, 88 S.Ct. 1868, 1873, 20 L.Ed.2d 889 (1968). This inquiry, as Mr. Justice Harlan aptly noted in his Katz concurrence, normally embraces two discrete questions. The first is whether the individual, by his conduct, has “exhibited an actual (subjective) expectation of privacy,” 389 U.S., at 361, 88 S.Ct. at 516-whether, in the words of the Katz majority, the individual has shown that “he seeks to preserve [something] as private.” Id., at 351, 88 S.Ct. at 511. The second question is whether the individual’s subjective expectation of privacy is “one that society is prepared to recognize as ‘reasonable,’ ” id., at 361, 88 S.Ct., at 516-whether, in the words of the Katz majority, the individual’s expectation, viewed objectively, is “justifiable” under the circumstances. Id., at 353, 88 S.Ct. at 512. See Rakas v. Illinois, 439 U.S., at 143-144, n.12, 99 S.Ct. at 430, n.12; id., at 151, 99 S.Ct. at 434 (concurring opinion); United States v. White, 401 U.S., at 752, 91 S.Ct., at 1126 (plurality opinion).
[1155]*1155Smith v. Maryland, 442 U.S. 735, 740, 99 S.Ct. 2577, 2580, 61 L.Ed.2d 220 (1979) (footnote omitted).
C.
At the outset, we agree with the Court of Appeals for the Fifth Circuit that a lower court’s determination that a reasonable expectation of privacy does or does not exist “is a legal conclusion involving substantive Fourth Amendment analysis . . . subject to full review by this court.” United States v. Vicknair, 610 F.2d 372, 379 (5th Cir. 1980). Accordingly, the district court’s statement that “[Ojne normally has a justifiable expectation of privacy in the trunk of one’s car, no matter where it is parked,” is not insulated by the clearly erroneous standard of review. Underlying facts supportive of the district court’s legal conclusion are, of course, so insulated.
We assume that Ramapuram had an actual subjective expectation of privacy in the trunk of the “junker.” He firmly desired to keep secret any item placed there, particularly the dynamite.
We do not conclude, however, that Ramapuram’s actual expectation of privacy was legitimate or reasonable or justifiable. First, the district court found and concluded that the “junker” was located in an open field. See Hester v. United States, 265 U.S. 57, 44 S.Ct. 445, 68 L.Ed. 898 (1924); Johnson v. United States, 333 U.S. 10, 68 S.Ct. 367, 92 L.Ed. 436 (1948); United States v. Brown, 487 F.2d 208 (4th Cir. 1973) (per curiam), cert. denied, 416 U.S. 909, 94 S.Ct. 1617, 40 L.Ed.2d 114 (1974). Under the doctrine of Hester, no Fourth Amendment protection extends to open fields. Accordingly, for example, if the object of McMonagle’s search had been the “junker” itself, rather than the contents of the “junker’s” trunk, then Ramapuram clearly would not be heard to complain of the trespass by McMonagle to ascertain the identity of an auto immobilized where the “junker” was immobilized. Counsel for Ramapuram has concentrated his argument on the difference between the altogether visible exterior of the “junker” and the concealed interior of the trunk. His position encompasses the point that the dynamite was enclosed in the “junker” itself rather than left uncovered in high grass or in a tree, cf. Patler v. Slayton, 353 F.Supp. 376, 383 (E.D.Va.1973), aff’d 503 F.2d 472 (4th Cir. 1974). The thrust of counsel’s argument is that the covered, closed character of the junker’s trunk foreclosed any right to open it. The district court agreed. See also United States v. Diaz-Segovia, 457 F.Supp. 260, 268-70 (D.Md.1978). But see Cady v. Dombrowski, 413 U.S. 433, 449-50, 93 S.Ct. 2523, 2531, 37 L.Ed.2d 706 (1973) (specifically leaving the question open as to back seat of automobile in open field). It is sufficient here to observe that whatever expectation of privacy attends a closed but unsecured “effect” generally is diminished where the “effect” itself is placed in an area totally without the protection of the Fourth Amendment such as in an open field. United States v. Jackson, 585 F.2d 653, 658-59 (4th Cir. 1978). See United States v. Williams, 581 F.2d 451, 453 (5th Cir. 1978), cert. denied, 440 U.S. 972, 99 S.Ct. 1537, 59 L.Ed.2d 789 (1979) (“Although the expectations of privacy test has done away with outmoded property concepts no longer satisfactory for fourth amendment analysis .. . the distinction between open fields and curtilage is still helpful in determining the existence or not of reasonable privacy expectations.”); cf. United States v. Alewelt, 532 F.2d 1165, 1168 (7th Cir.), cert. denied, 429 U.S. 840, 97 S.Ct. 114, 50 L.Ed.2d 109 (1976) (privacy expectations as to the pockets of a jacket diminished where jacket left on coat rack in “general work area”).
Second, although we agree with the district court that the “automobile exception” is inapplicable to this case,10 nevertheless, we cannot ignore the fact that it was an automobile that was searched. Courts have [1156]*1156long recognized the lessened expectation of privacy attendant to an automobile. Cf. United States v. Newbourn, 600 F.2d 452, 454, 457-58 (4th Cir. 1979); United States v. Torch, 609 F.2d 1088, 1091 n.3 (4th Cir. 1979). Accordingly, we decide on the basis of the actual characteristics of the container before us, and not on the basis of different kinds of containers which may present themselves in other cases.11 Nor need we determine whether the automobile was abandoned in any constitutional sense. But see United States v. Wilson, 472 F.2d 901, 902 (9th Cir. 1972).
Third, despite Ramapuram’s general rights of dominion over his own property, the question is not thereby answered. It remains a question of whether, regardless of the state of ownership,12 he had a reasonable expectation of privacy. Rawlings v. Kentucky,-U.S.-, 100 S.Ct. 2556, 65 L.Ed.2d 633 (1980). Ramapuram failed to secure the trunk of the “junker” and, indeed, could not have done so in the normal manner by locking it inasmuch as the lock assembly had been earlier removed. “The character of the invaded place is clearly important.” United States v. Torch, 609 F.2d at 1091 n.3. Ramapuram did not live on the farm where the “junker” was located; accordingly, however much such a factor might augment the abstract right to exclude, such augmentation is not present here. Cf. Torch, 609 F.2d at 1091 (Absence at the time of the search diminished the strength of an expectation of privacy). The residence on the farm was leased to others. Additionally, the farm was used with permission by persons who were neither members of the Ramapuram family nor residents on the farm. It is, of course, true that a sharing of premises does not by itself dissipate the reasonable expectations of privacy of those with joint control over the premises.13' Here however, Ramapuram’s possessory interest in the farm and “junker” was sufficiently lessened to compel the judgment that he could not legitimately expect that the contents of the unlocked trunk of the “junker” situated in an open field would remain secure from prying eyes, irrespective of whether those eyes were private or governmental. Cf. United States v. Vicknair, 610 F.2d at 380.
As to the stolen dynamite, Ramapuram did not take “precautions customarily taken by those seeking privacy." Rakas v. Illinois, 439 U.S. at 152-53, 99 S.Ct. at 435 (Powell, J., concurring). No testimony established that the “junker” was used by Ramapuram or members of his family for storage of personal effects or any other significant purpose. Cf. United States v. Basile, 569 F.2d 1053, 1059 (9th Cir. 1978) (Hufstedler, J., dissenting). Neither Ramapuram’s possessory interests nor his correlative but unadorned right as the owner to exclude others, under the circumstances of this case, are. sufficient to raise his actual expectations of privacy to a level of constitutional legitimacy. See United States v. Vicknair, 610 F.2d at 381.
Taking the above considerations in combination, and whether the conclusion is cast in terms of Ramapuram’s standing or on the basis that McMonagle’s lifting of the trunk lid of the “junker” and his perusal of its contents did not constitute a “search” within the contemplation of the Fourth Amendment, it suffices to hold that no privacy interest protected by the Fourth Amendment was invaded and that therefore no proper case for the application of the exclusionary rule has been made out.
II.
Ramapuram asserts error in the trial court’s refusal to instruct the jury as to the [1157]*1157meaning of the word “substantial” in its instructions on the insanity defense and in the court’s like refusal to instruct the jury that “criminality” of conduct in the federal insanity test means moral rather than criminal wrongfulness. Counsel, at oral argument, having, we think, sensibly withdrawn from our consideration the latter issue, we determine that the former is also lacking in merit. Language is by its very nature an approximation. In any search for absolutism in conveyance of a meaning, each addition of words by way of definition of words already employed only invites demand for further clarification of additional words introduced as part of the definition.
Of course, a demand for specificity where words employed are inherently unclear or ambiguous, may well be justified. However, reading the district court’s charge in its entirety demonstrates that the trial judge made readily comprehensible to the jury what the significance was of the words utilized: “substantial capacity.” There is no showing here that the jury failed to understand or properly to apply the trial court’s insanity charge. See United States v. Butler, 409 F.2d 1261 (4th Cir. 1969).
III.
In United States v. Ramapuram, 432 F.Supp. 140 (D.Md.1977), aff’d, 577 F.2d 738 (4th Cir.) (unreported), cert. denied, 439 U.S. 962, 99 S.Ct. 309, 58 L.Ed.2d 318 (1978), we affirmed the district court’s holding that the government timely filed its second certification, pursuant to 18 U.S.C. § 5032, to the effect that the state juvenile court refused to assume jurisdiction over the case against Ramapuram. We have no occasion to reexamine that decision.
Finally, we think the contention that the pendency of the appellate proceedings in the juvenile case ousted the district court’s jurisdiction under the instant indictment lacks merit. They were separate and distinct proceedings.
AFFIRMED.