Police may enjoy special immunity. In Liser v. Smith, 254 F. Supp. 2d 89, plaintiff was "exposed" by releasing an ATM photo of him in a murder case (but it turns out he was innocent). The court observes
Under D.C. law, government officials have absolute immunity in actions
for libel and slander - even if their statements are false and
defamatory - provided that two conditions apply. First, the official
must have acted within the "outer perimeter" of his official duties;
second, the particular government function at issue must have been
"discretionary" as opposed to "ministerial."
Which means, was it part of the officials duties (seeking public help in locating a suspect is)? As to the "discretionary" test, there's a 4-part juggling act which I honestly have not internalized, but seems to come down to asking "would the government rather not be sued?". The net result in this case was that the government was held to be immune from suit (hence issues of truth are irrelevant).
In Gillan v. City of San Marino, at a press briefing, a police lieutenant stated that Gillan "sexually molested a member of last year's girl's basketball team on several occasions" (Gillan was in fact innocent). The full content of the press briefing was not revealed, since the court says that
A public employee acting within the scope of employment is immune from
liability for an injury caused by the employee's "instituting or
prosecuting any judicial or administrative proceeding․ even if he acts
maliciously and without probable cause."
and this includes defamation. This court held that
Acts undertaken in the course of an investigation, including press
releases reporting the progress or results of the investigation,
cannot give rise to liability. (Ingram, supra, at p. 1293, 89
Cal.Rptr.2d 60 [held that statements concerning an investigation that
were made in a press release “were part of the prosecution process”
and therefore immune]
On the other hand, in Harrington v. Wilber 353 F. Supp. 2d 1033, we have a plaintiff who had been convicted of murder, but 25 years into the life sentence it was revealed that the prosecutor has failed to reveal an alternative suspect, and the conviction was overturned. The current prosecutor and defendant in the instant case announced that they would discontinue prosecution of Harrington. This was announced at a press conference, where defendant uttered a number of defamatory statements, including
"After personally spending hundreds of hours on this case, I have no
doubt that Terry Harrington committed the murder of John Schweer on
July 22, 1977. The jury made the right decision in 1978, and the right
man went to prison for over twenty-five years."
Harrington sued, the case was summarily dismissed on the grounds that
1) Wilber's statements are protected as First Amendment opinion;
2) Wilber's statements are protected by an absolute privilege because
they were incidental to the termination of a judicial proceeding;
3) Wilber's statements are protected by qualified privilege;
4) Wilber's statements were discretionary acts immune from liability
under the Iowa Municipal Tort Claims Act
which leads to his appeal in US District court. The court reversed the dismissal, because the statement was not opinion (saying "I have no doubt" doesn't make a defamatory statement into opinion).
The court also rejected absolute immunity because:
The plain language of Buckley holds that prosecutorial press
conferences, though perhaps necessary, are not entitled to absolute
immunity. Indeed, while the press conference here at issue may have
served a valuable public service, it was not incidental to any
proceeding in the manner intended by the absolute immunity privilege
This is in clear contrast to Liser, where the police were performing the essence of their task, in tracking down a murderer. The difference between Gillan and Harrington is subtle, to say the least.