The Court intentionally crafted its opinion knowing that Jackson would be unlikely to comply if the executive branch were forced to do something. In very basic terms, the legislature's job is to make law, the Court's job is to "say what the law is" (Marbury v. Madison) and the executive's job is to execute the law. Marshall was always very conscious of the legitimacy of the Court (read the background of Marbury to truly learn how his decision was brilliantly crafted), particularly on the issue of being defied by the President. The Court, on its own, is given no Constitutional power to enforce its rulings. It falls to the executive branch to enforce the law. Therefore, most of the time the President will ensure compliance.

However, the Court knew that Jackson would refuse to do so. Luckily, the issue in Worcester was that of a Georgia law and conviction of Worcester and Butler. Therefore, the Court was able to make a ruling that invalidated the Georgia law and vacated the convictions of the missionaries. It did not require, nor did it ask, Jackson to do anything. In typical Marshall fashion, he was able to navigate the political landmines surrounding the case while still getting his way and laying down very important precedent for tribal sovereignty.