As a member of the first Legislature, in 1819, he was the author of a law providing a fair trial by jury for slaves indicted for crimes above petty larceny, and in 1826 he became a regular contributor to the American Colonization Society, believing it to be an aid to emancipation.

The following year he was able to induce the Legislature, although he was not then a member of it, to pass an act forbidding the importation of slaves into Alabama either for sale or for hire.

This was regarded as a step preliminary to emancipation.
The cause of education in Alabama had in Birney a trusted leader.

During the year 1830 he spent several months in the North Atlantic States for the selection of a president and four professors for the State University and three teachers for the Huntsville Female Seminary.

These were all employed upon his sole recommendation.