They can be impeached for "bad behavior". At least by implication, which says that they serve for life "on good behavior".
The Judges, both of the supreme and inferior Courts, shall hold their Offices during good Behaviour,
Art. III Sec. 1)
The House of Representatives shall chuse their Speaker and other Officers; and shall have the sole Power of Impeachment.
Art. I Section 2
The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation. When the President of the United States is tried, the Chief Justice shall preside: And no Person shall be convicted without the Concurrence of two thirds of the Members present.
Judgment in Cases of Impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.
Art. I, Sec. 3
So, they can be impeached for "bad behavior" (The President can only be impeached for "high crimes and misdomeanors".)
So, the answer depends on the answer to the question, "Does ignoring the Constitution, or ruling in contravention to it, constitute 'bad behavior'?"
I'd say yes, but I don't get to decide, the House and Senate do. However taking a bribe would be an easier to make a case example of "bad behavior".