I hate to be the wet blanket on this anti tenure parade, but I'm sure many of you know why tenure laws were passed in the first place, but do not know how a tenured teacher can be dismissed anyway. Here in Pennsylvania, in some districts it was common practice to fire entire teaching staffs at the end of the year and rehire them on the bottom step of the salary scale. It was also common practice that when a school district official (perhaps a school board member's daughter) graduated with a teaching degree, a position was made for her by dismissing an older teacher with little in the way of cause. So eventually a system was put in place where a teacher could be dismissed if it was proven that he/she was guilty of five different types of offense, including immorality and intemperance. Being convicted of a felony, gross insubordination, and incompetence were the other grounds for dismissal, but such charges had to be proven and could not simply be stated without proof. Therein lies the problem and it is twofold.
First off, administrators do not like to fire teachers because it requires them to actually do some real work. They have to evaluate the teacher according to a system that is established by law, and if a teacher is unsatisfactory, they have to rate him/her so, which is likely to be challenged. Such a challenge might seem to be an unsurmountable obstacle, but it is not. It requires another administrator to do an evaluation, which if it concurs, can result in a tenure dismissal hearing. The teacher has the right to be represented at that hearing. Second, like police officers and other public employees (let's not go into private sector unions at this time), when a teacher is threatened by the system, all of them tend to band together in defense of the threatened member. This is human nature, and it is not in and of itself wrong. It just is.
While lots of cases can be brought to prove that the tenure law is a bad law, especially in places like New York City where the teachers' union is very strong and the administration very poor and weak willed, in most teaching districts is does not present insurmountable problems. In the district in which I taught, two teachers were dismissed under the tenure act during my career. While a few others might have been ineffective or incompetent, most were salvageable with help, which they got. A few got through entire careers with satisfactory ratings since they were friends of their supervisors or the supervisor did not want to make waves (not the fault of the tenure law, is it?). In short, with good and tough administration, a school district can be very effective in weeding out dead wood. That weeding has to start at the top, not the bottom in most cases.
In conclusion, it is easy to blame teachers for the problems brought upon us by a liberal power structure, but in most cases they are not at fault.