Opening the debate on Parliament's R2.2 billion budget, Mbete quoted the Constitution at length, saying it spelled out the separation of the three arms of state (Executive, Parliament and Judiciary) clearly.
"The principle of separation of powers recognises the independence of the branches of government...," she said.
"...The principle of checks and balances focuses on the importance of ensuring the constitutional order prevents the branches of government from usurping power from one another. In this sense, it anticipates or seeks to prevent the intrusion of one arm of government into the terrain of another."
In recent months, Mbete and Parliament has been cited as respondents in court actions launched by opposition parties. This included a case where opposition parties want a secret ballot when the debate on the motion of no confidence in President Jacob Zuma takes place.
The Constitutional Court has yet to rule on the matter. Mbete warned against judicial overreach.
"With structures such as the rules committees, the chief whips' forum and the committee of chairpersons, we are well placed to meaningfully resolve disagreements and effectively execute our mandate without inviting the courts to encroach on our constitutionally protected terrain."