ICJ inquiry

Time again for the test-your-international-knowledge quiz that we call puzzler.
In the 2011 lecture described in a recent post, Judge Christopher Greenwood of the International Court of Justice remarked:

[S]ince 1981 there has been only one case (out of fifty) in which a State has declined to appear and only in the later phase of the proceedings, although many of the cases involved vigorous challenges to the jurisdiction of the Court.

Today's puzzler: Name that nation-state, and that case. Answer below.

(photo of Peace Palace courtesy of ICJ website)