I think part of the issue is no matter the importance of the case sometimes the money will not be spent. Also, the higher ups want to see that all possible avenues have been exhausted before approving the expenditure. Final thing is you might still be able to make a case without the data on the device so once it is known that there is no other way than paying for the unlock/extraction they might say move on.
The other issue is whether or not those who unlock the device will testify in court. That's another added cost that has to be weighed in as well.
Not attacking anyone just laying out the issues that revolve around a case and what investigators tend to deal with.
The other issue is whether or not those who unlock the device will testify in court. That's another added cost that has to be weighed in as well.
And there is even a further one IMHO.
As passcodeunlock said, when dealing with this kind of "experimental" and "high technology" approaches, there is a certain level of risk on the integrity of the device/evidence
The processing is manual, not some click-forensics based stuff. A single mistake is enough to brick the phone and your data is gone forever.
Which poses two kinds of questions
1) the reliability, "good name", etc. of the laboratory
2) the authorizations needed, once a laboratory has been chosen, to risk the procedure
In more traditional "wet forensics" the tests on evidence are usually categorized in two sets
a. repeatable
b. non-repeatable <- usually - at least here in Italy - these are performed only at the presence of both prosecution and defense lawyers and experts[1] with a specific authorization by the Court.
In the case of an experimental method that has concrete possibilities to brick the phone and make data lost forever, extracting the data (which should be in theory a repeatable test/method) soon becomes a "possibly non-repeatable" method, and should be treated, to be on the safe side, definitely as a "non-repeatable" one.
jaclaz
[1] a typical example is tests (chemical, DNA, etc.) in cases where the amount of biological matter to be analyzed is enough to allow only one test