During good behavior

while (or so long as) one conducts one's self with integrity and fidelity or with propriety.

See also: Behavior

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
If we resort for a criterion to the different principles on which different forms of government are established, we may define a republic to be, or at least may bestow that name on, a government which derives all its powers directly or indirectly from the great body of the people, and is administered by persons holding their offices during pleasure, for a limited period, or during good behavior. It is ESSENTIAL to such a government that it be derived from the great body of the society, not from an inconsiderable proportion, or a favored class of it; otherwise a handful of tyrannical nobles, exercising their oppressions by a delegation of their powers, might aspire to the rank of republicans, and claim for their government the honorable title of republic.
The regular distribution of power into distinct departments; the introduction of legislative balances and checks; the institution of courts composed of judges holding their offices during good behavior; the representation of the people in the legislature by deputies of their own election: these are wholly new discoveries, or have made their principal progress towards perfection in modern times.
The Judges, both of the supreme and inferior Courts, shall hold their Offices during good behavior, and shall, at stated Times, receive for their Services, a Compensation, which shall not be diminished during their Continuance in Office.
The Constitution says that members of the judiciary 'shall hold office during good behavior until they reach the age of seventy years...' Though he will celebrate his 70th birthday only on Monday, July 29, he will say his farewell three days earlier, because the Court interprets this constitutional provision to mean 'until midnight of the day before reaching their 70th birthday.'
The SC justices hold office during good behavior until they reach the age of 70, or become incapacitated to discharge their duties.
Article 71 of the Liberian Constitution says the Chief Justice and Associates Justices of the Supreme Court and the judges of subordinate courts of record shall hold office during good behavior.
Section 11 of Article VIII of the constitution provides that members of the Supreme Court "shall hold office during good behavior until they reach the age of seventy years or become incapacitated to discharge the duties of their office."
As laid out in (http://judiciallearningcenter.org/article-3-and-the-courts/) Article III of the Constitution , "judges, both of the supreme and inferior courts, shall hold their offices during good behavior," meaning they can keep their jobs for as long as they want unless they are impeached.
Englishmen were jealous of judicial independence and upset when Charles I changed the usual tenure so that judges no longer served during good behavior but at the king's pleasure, bringing them under closer royal control.
The Constitution clearly states that justices will serve "during good behavior." We all agree treason is not good behavior.
The Constitution says federal judges can stay on the bench "during good behavior"--which, barring impeachment, means a lifetime appointment.
"The science of politics...like most other sciences," claimed Alexander Hamilton, "has received great improvement....The regular distribution of power into distinct departments...legislative balances and checks...judges holding their offices during good behavior; the representation of the people in the legislature by deputies of their own election...are means, and powerful means, by which the excellences of republican government may be retained and its imperfections lessened or avoided..."