The ASTI is to consider holding a national ballot of its members to select its next general secretary.
Following a private meeting of the union's executive yesterday, delegates overwhelmingly voted to support a motion calling for consideration to be given to the move.
This would mark a significant departure from previous methods of selection, and would be similar to the approach taken by the INTO.
The central executive of the ASTI also voted to seek further clarification as to whether the next general secretary should be offered a fixed-term or open contract.
Sources said this could mean the union would avoid the possibility of any future general secretary seeking an injunction against being removed from the post.
In a separate development, the Department of Education is to be given one month to review its guidelines on school inspections or else face legal action by the ASTI.
Executive members voted by a large majority to support a motion calling on the ASTI to initiate legal proceedings against the Department if it does not withdraw a booklet which outlines the way inspections at second level should take place.
The ASTI's concerns centre on the fact that it was not consulted by the Department when its "Guide to Subject Inspection at Second Level" was being drawn up.
A letter from the ASTI to the Department outlining its position is expected within days.
The motion at the executive meeting stated: "That the ASTI proceed on May 16th with court action to force the Department of Education and Science to refrain from breaching Section 3.13 (8) of the Education Act should the Guide to Subject Inspection at Second Level not be withdrawn by that date."
The news that the ASTI is considering taking legal action against the Department of Education marks a significant hardening of its stance on the issue of school inspections.
At its annual conference in Killarney earlier this week, it was revealed that the union had decided to advise its members to accept inspectors into their classrooms.
Previously, ASTI policy had been to support any member who refused to teach in front of an inspector.