United States Marine corps casualty assistance
calls officers wear blue dress uniforms when they notify next of
kin that their Marine has been killed or wounded in the line of
duty. The notifier's rank must be equal to or higher than that of
the deceased -- unless the next of kin is also in the military. In
that case, the notifier must be of a rank equal to or above the
next of kin.
'It's the toughest thing I've ever done', says Maj. Eric A. Putman,
the notifier for Pennsylvania from from Reading to Johnstown. He
doesn't leave until a friend or relative arrives. (
This Marine's toughest duty is being the messenger).
Now, apparently, blue dress is out, and service 'A' uniforms are to
be worn:
Wearing of dress blues barred on casualty notification
calls).

Blue Dress Uniform Service 'A' Uniform