For the 10th anniversary of the American Film Institute’s list of the 100 best American movies, they allowed re-balloting and added movies from the last ten years. It is important to understand how the ballot worked. First, they limited the nominees to 400 movies, including 45 movies that came out since the last list. You could write in a movie, but I don’t know what chance a write-in would have. Instead of having people rank the movies, they just had people pick 100. Then you would rank your top 5 which was used as a “tie-breaker”.
Some of the criteria for selection were cut and dry. There had to be significant American involvement and it had to be feature-length (60 minutes or more). The rest of the criteria are more flexible:
Critical Recognition
Major Award Winner
Popularity Over Time
Historical Significance
Cultural Impact
Note that liking the movie supposedly has nothing to do with the decision. Even some of these criteria could be ranked objectively, like critical recognition, award winner, and popularity.