The ruling does not cover cell phone data or GPS devices that deliver data
to a third party.
Cell phone records are not the papers or effects of the person being
investigated, they belong to the cell phone company. The Supreme Court
"consistently has held that a person has no legitimate expectation of
privacy in information he voluntarily turns over to third parties."(442
US 735,743-744)[1] That
quote is from the Court's ruling in a case that was specifically about
police getting a record of telephone calls that a suspect made,
Smith v. Maryland, 442 U.S. 735 (1979)[2].
Congress laid out rules for police obtaining such records in the Electronic
Communications Privacy Act (ECPA) of 1986[3]. The ECPA doesn't specifically
mention cell phone location information (since this was 1986), but it does
include "name; address; local and long distance telephone connection
records, or records of session times and durations; length of service
(including start date) and types of service utilized; telephone or
instrument number or other subscriber number or identity, including any
temporarily assigned network address; and means and source of payment for
such service (including any credit card or bank account number)."
A court order may be issued under section 2703(d) of the ECPA[4] "only if
the governmental entity offers specific and articulable facts showing that
there are reasonable grounds to believe that … the records or other
information sought, are relevant and material to an ongoing criminal
investigation."
This is a lower standard than for a search warrant. A warrant
requires "probable cause", that is "information sufficient to warrant a
prudent person's belief that … evidence of a crime or contraband would
be found in a search".
[1] http://supreme.justia.com/us/442/735/case.html#743
[2] http://en.wikipedia.org/wiki/Smith_v._Maryland
[3] http://en.wikipedia.org/wiki/Electronic_Communications_Priva...
[4] http://www.gpo.gov/fdsys/pkg/USCODE-2010-title18/html/USCODE...