Isn't the defense attorney an officer of the court, as is the judge?
Yes, a defense attorney IS an officer, but his office is NOT to give orders and he cannot enforce orders. His office is to plead, to advocate, to present a case -- or one side of a case -- in as persuasive a manner as his skills and the law allow.
A judge on the other hand umpires the pleading according to the rules of evidence and that sort of thing, and advises the jury -- often the very advice he gives is scrutinized by both sides before it is given, and the sides may make suggestions for the instructions he gives the jury. But those instruction are on the law and they are given in "one the one hand, on the other hand" fashion.
For example, "If you find that the defendant did intend to make Mr. Paulsen fear for his life or safety, then you may find him guilty of assault. If, on the other hand you find that the defendant had no intention of causing any fear or apprehension in Mr. Paulsen, but drove at him in his SUV and ninety-eleven miles per hour in a narrow alley with high buildings on either side COMPLETELY inadvertently, then you may find him guilty of negligence, but not of assault." An advocate, who is not supposed to be impartial could say, "It cannot be shown beyond a reasonable doubt that the defendant has ever been inside an SUV, so you cannot find him guilty." But the advocate for the other side can then say, "the evidence we have presented, the video, the fingerprints, the signed confession, all indicate that the defendant ..." well you get the point ...