The Taqleed of a scholar who is a Mujtahid in his school

A scholar who is a Mujtahid in his school follows and adopts an absolute
Mujtahid's principles of extracting and deriving rules [usool] but possesses the ability to
extract laws directly from the Quran and Sunnah. Such a Mujtahid may differ with his
Imam on certain details and rules but follows the majority of the rulings with in the
school. Imam Abu Yusuf and Imam Muhammed from the Hanafi school; Imam Muzni
and Imam Abu Thaur from the Shaf'iee school; Imam Sahnoon and Imam Ibn Qasim from
the Maliki school and Imam Ibrahim al-Harbi and Imam Abu Bakr al-Athram from the
Hanbali school are all examples of Mujtahids with in their respective schools who
differed with the founders of their schools, Shaykh Ibn Abi Deen introducing these
scholars writes:
"The second level [of Mujtahids] are those who are Mujtahids in their school of
thought like Abu Yusuf and Muhammed and all other Hanafi scholars who are capable of
deriving rules from the above mentioned proofs based on the principles of their teacher
(Imam). These scholars, although differing with their teacher in certain details, follow
him in the bases of his principles."

This is the reason why Imam Abu Yusuf and Imam Muhammed are considered to
be Hanafi scholars even though they differed with Imam Abu Hanifa in many details.