MP doctor quits parliament

The rogue MP was dumped as assistant health minister last week for breaching cabinet solidarity when he spoke out against changes to the state's corruption watchdog and doctor contracts.

At the time, Dr Davis said he had stood on some powerful toes and was demoted partly because he raised concerns with Premier Campbell Newman about looming changes to political donations.

His dissatisfaction came to a head on Thursday night, when he told parliament he couldn't support his government's policy to remove caps on political donations and raise disclosure thresholds.

He left the chamber before the laws were put to a vote.

While he says his sacking was a catalyst to his immediate departure, the accumulation of controversial legislation had weighed heavily on his conscience.

"The passage of recent government legislation affecting critical aspects of our democracy goes contrary to my value system and that of the majority of my electorate,