The president has been accused of manipulating the judiciary to get convictions against his opponents. Sri Lanka's former army commander Sarath Fonseka was convicted in a few cases since he challenged Rajapaksa in the 2010 presidential election.
Bandaranayake is an unlikely government foe.
Her elevation to chief justice came months after she supported a ruling that said Rajapaksa needed only a parliamentary vote -- not a national referendum -- to amend the constitution to expand his powers and let him serve more than two terms.
But the government and judiciary have repeatedly clashed during her short term in office.
In July, a mob reportedly instigated by a government minister attacked a courthouse with stones in the northern Mannar district because they disagreed with a judge's ruling. The Bar Association of Sri Lanka said the minister threatened the judge in a phone call. Bandaranayake demanded action against the attackers.
In September, the Judicial Services Commission, a disciplinary body for judges that Bandaranayake heads, accused unnamed "powerful persons" of trying to interfere in its work. It said judges and their families were under threat and living in fear.
Commission secretary Manjula Tillakaratne was later beaten in broad daylight last month as he sat in his parked car. Opposition parties blamed the government, which denied responsibility. Police have made no arrests.
Judges and lawyers boycotted courts in protest.
The impeachment complaint against Bandaranayake -- submitted earlier this month to Parliament's speaker, the president's older brother -- followed a Supreme Court ruling that declared Rajapaksa's effort to take back some powers from the provinces to be unconstitutional.
The ruling angered the government by showing how it had reneged on its promise to strengthen provincial councils as part of a plan to empower minority Tamils and defuse the nation's ethnic conflict, said Jehan Perera, an analyst with the National Peace Council activist group.
