Answer:
A judge overturns a legal precedent.
Step-by-step explanation:
A judge who's an activist will mostly wants to leave its own imprint on the case. This judge will certainly NOT refer that to Congress, nor will base his judgement on precedents nor to uphold a lower court's ruling.
He will overturn a legal precedent, trying to make a new legal precedent and re-write the law into his own views, bypassing the decisions of his colleagues in previous similar cases, and the text of the laws adopted by Congress.