Often in a pleading you are tempted to give your strongest argument and ignore case law and contrary authority that is inconsistent with your argument. Depending on the pleading and the situation, you are generally safe to ignore contrary authority and assume it will be brought up by the other party, especially where it is easily distinguishable by the facts of your case, and is from a lower court with less weight than the cases you have cited. Why do the opposing attorney’s work, and bring up issues that really are not relevant?
But, where there is strong relevant authority for both sides, and courts have made contradictory rulings, it is in your best interest to let the court know about this contrary authority, and explain why the line of case law you want to be followed is the most dispositive. The outcome often hinges on the level and jurisdiction of the judge whose ruling is against your position. If the ruling is from the state supreme court in your jurisdiction, and the other ruling is from a federal appellate court, you have a much stronger argument that the state supreme court ruling should have precedence (unless, of course, you are in federal court or are dealing with a federal issue).
When to make this pitch to the court is a tactical matter. If the opposition brings it up in a responsive pleading, you have lost the opportunity to get first crack at it and to appear balanced and reasonable. However, if you are already dealing with complicated issues with a long and convoluted fact pattern, you might not want to muddy the waters by bringing it up in your initial law and motion pleading. This decision needs to be made on a case by case and pleading by pleading basis.
Even if you decide to wait, realize that this contrary authority is coming, and draft your response to it before receiving the responsive pleading from the other side. This way you won’t be under a time crunch to draft your reply. And if you are lucky, you will just have to make some minor revisions depending upon the contents of the other side’s pleading.