"The judge drinks coffee."
Translation:Yargıç kahve içer.
Because "the judge" is the SUBJECT of the sentence. You always use the NON-MODIFIED form of the word for the subject of a sentence, whether you mean "the [noun]" or "a [noun]." But if you do mean "a [noun]," then you use the non-modified form, but you add "bir" in front of it (sorry for all caps, which I'm using in place of italics for emphasis):
Yargıç ekmek yer. "The judge eats bread." Bir yargıç ekmek yer. "A judge eats bread."
You use the "yargıçı" form to mean "the judge" only for OBJECTS in sentences. In the following examples, the judge is the object of the action:
Aslan yargıç yiyor. "The lion is eating a judge." Aslan yargıçı yiyor. "The lion is eating the judge."
Duo-experts, please correct me if I've erred!