The Florida senate recently passed a bill that would abolish tenure for teachers.
Since I am a tenured professor and worked hard to get it, I (obviously enough) have a generally positive view of tenure, at least at the university level. However, I can understand the concern that tenure makes teachers unfireable, even when they are doing a poor job. However, that is not so much a problem with tenure itself as with the way tenure is earned. A proper tenure procedure should serve to eliminate the unqualified.
At the university level, getting tenure is usually an ordeal. It takes about six years to earn tenure and usually requires meeting rather high standards (such as minimum number of publications, having good evaluations, and so on). The application also has to make it through several levels of evaluation, beginning with a department vote and going all the way up to the top of the university system. While some unqualified professor do get by, this is the exception rather than the rule.
As such, it seems that the problem that eliminating tenure is supposed to solve could also be addressed by keeping tenure and improving the process and standards.
Naturally, it can be argued that tenure itself is a problem. After all, tenure provides an almost unmatched level of job security and this might lead many teachers to simply start coasting at the minimal level once they achieve it.
I will admit that I have seen faculty at various universities do just that. However, this is also the exception rather than the rule. Also, being tenured does not confer immunity to being fired-it just provides a considerably degree of protection, mostly intended to provide protection for academic freedom. A professor who fails to do her job can be fired.
It can also be argued there is really no need for tenure in public K-12 schools. After all, matters such as academic freedom or protecting educators from being arbitrarily fired are not really significant at this level. Also, people who work in the private sector generally have no real job security at all, so teachers should not enjoy such a privileged status.
These arguments do have some appeal. Of course, getting rid of tenure might also run afoul of the attempts to recruit and keep better teachers.
In any case, we will soon have some empirical data about what effect the removal of tenure will have on education. Florida is the first state to do this, so this will be a learning experience.