In Ontario v. Quon, Justice Kennedy noted that he approaches privacy issues in the technological realm with great caution:

The Court must proceed with care when considering thewhole concept of privacy expectations in communications made on electronic equipment owned by a government employer. The judiciary risks error by elaborating toofully on the Fourth Amendment implications of emerging technology before its role in society has become clear. See, e.g., Olmstead v. United States, 277 U. S. 438 (1928), overruled by Katz v. United States, 389 U. S. 347, 353 (1967). In Katz, the Court relied on its own knowledgeand experience to conclude that there is a reasonable expectation of privacy in a telephone booth. See id., at 360–361 (Harlan, J., concurring). It is not so clear that courts at present are on so sure a ground. Prudence counsels caution before the facts in the instant case are used to establish far-reaching premises that define the existence, and extent, of privacy expectations enjoyed by employees when using employer-provided communication devices.

Rapid changes in the dynamics of communication and information transmission are evident not just in the technology itself but in what society accepts as proper behavior. As one amici brief notes, many employers expect or at least tolerate personal use of such equipment by employees because it often increases worker efficiency. See Brief for Electronic Frontier Foundation et al. 16–20. Another amicus points out that the law is beginning to respond to these developments, as some States have recently passedstatutes requiring employers to notify employees whenmonitoring their electronic communications. See Brief for New York Intellectual Property Law Association 22 (citing Del. Code Ann., Tit. 19, §705 (2005); Conn. Gen. Stat. Ann.§31–48d (West 2003)). At present, it is uncertain howworkplace norms, and the law’s treatment of them, willevolve.

…

A broad holding concerning employees’ privacy expectations vis-à-vis employer-provided technological equipment. might have implications for future cases that cannot be predicted. It is preferable to dispose of this case on narrower grounds.

In other words, because technology is evolving so quickly, and the Court doesn’t really understand how things work, the Justices would rather be more cautious in laying down broad rules. They allege that Olmstead was decided before technology’s “role in society has become clear.” Later, when the technology was better understood, Katz overrruled Olmstead. In light of the Court’s uncertainty over how text messages work, perhaps this is the prudent path.

Yet, Scalia disagrees:

Applying the Fourth Amendment tonew technologies may sometimes be difficult, but when it is necessary to decide a case we have no choice. The Court’s implication, ante, at 10, that where electronic privacy is concerned we should decide less than we other-wise would (that is, less than the principle of law neces-sary to resolve the case and guide private action)—or that we should hedge our bets by concocting case-specific stan-dards or issuing opaque opinions—is in my view indefen-sible. The-times-they-are-a-changin’ is a feeble excuse for disregard of duty.