20 Law Commission Report
CHAPTER 7: Computer searches
document driven and that previewing is too limited a search method. The police
either use preview searches or search forensically copied material, depending on
the nature of the information sought.
7.38
Previewing will be a suitable search method in the case of less complex searches
for readily accessible discrete data, where the search can be conducted relatively
quickly (so that the search subject is not deprived of their computer for an
unreasonably long period). Otherwise, we accept that for more complex searches
where some data may not be readily accessible or may not exist discretely, or for
lengthy searches, forensic copying should be the preferred sear
Current New Zealand law
7.39
The use of specialist search methods to conduct computer searches does not fit
comfortably within the current search and seizure framework. The main
difficulties are:
The data storage device must be removed from the search premises as a
precursor to searching the device. a search warrant authorises a constable to
seize gany thing which there is reasonable ground to believe will be evidence
as to the commission of an offence punishable by imprisonmenth.37 if the
material has not been viewed prior to removal, it will be difficult to form the
necessary belief required to authorise the seizure of the computer hard drive
(or a forensic copy).38
Seizure of computer data is not selective. The removal of the computer hard
drive involves the removal of a substantial amount of irrelevant material as
well as any relevant material.39 c
oncerns also arise where data removed may
include legally privileged material.40
7.40
Because of these difficulties, the extent to which enforcement agencies may
utilise specialist search methods in order to execute a computer search is unclear.
d ifferent approaches can be discerned from New Zealand case law.
7.41
in Calver v District Court at Palmerston North,41 the high court held that,
notwithstanding the practical difficulties that may arise where the number of
documents to be searched is large or stored on a computer, section 198 does not
authorise irrelevant material to be seized. The necessary sifting process to
determine relevance must be carried out on the warrant premises unless the
owner consents to its removal.
7.42
Other high court decisions have not rejected the use of specialist search methods
such as forensic copying, although in some of those cases there were other
37 Summary Proceedings
a
ct 1957, ss 198(1)
38 There is also an issue as to whether the removal of a forensic copy constitutes a seizure. See, for example,
v ictorian Parliament
l
aw Reform
c
ommittee
Warrant Powers and Procedures, Final Report (No 170 of
Session 2003-2005, Melbourne, 2005) 296-297.
39 Calver v District Court at Palmerston North [2005] dcR 114, 130 (hc) Miller J: gSeizure of material for
later sifting into that which is relevant and that which is not is still a search and seizure in obedience
to the warrant. The issuer must believe on reasonable grounds that all of the material to be seized will
be evidence of the offence.h i
t was noted that alternative options to forensic copying were available to
the police in the circumstances of the case.
40 See further, chapter 12, paras 12.95-12.108.
41 Calver v District Court at Palmerston North, above n 39.
