I assume that you are asking about the case of Lionel Brogden v. State of Maryland.  This was a case from 2004.

If this is the case you are asking about, the case was appealed because of a set of supplemental instructions given by the judge to the jury in response to questions that the jury had.

The defense argued that the judge's instructions to the jury were improper.  This was because the judge brought up a possible defense to the charge against the defendant.  The defense appealed on the grounds that this defense had nothing to do with the case and had never been put forward by the defense itself.

So, the point at issue here was whether the judge made a reversible error by bringing up this defense when the defendant and his lawyers had not put that particular defense forward themselves.