Ok since so many of us are going through this, let me first say....AAARRRGGGGGGGG!
First, get an advocate if you can.
Second, write a formal letter once again requesting a functional behavior analysis. If it is the same dummies that did it last time, sigh... then make sure you ask for the district to have specialists in your child's area do it from outside of your school. If they wrote pbis without doing this then they need to do the right thing this time. Research shows when a plan is made without the actual data, the guesses that teachers/staff make about why a behavior is being done are typically wrong. And the "go to" explanation is usually that the child wants attention or that they are trying to get out of work. Even if these things are true, it means that the child needs to learn to get attention in positive ways and the work needs to be adjusted and skills taught to be able to do the work.
--an fba needs to define specific behaviors, then collect data about where it happens, what happens before the behavior, how it is dealt with and what the effects are. They can examine this plus his assessment to see if he has the skills to deal with things better, to see if he is escaping something, to see if they are triggering it or if anything in the environment is triggering it etc.
--an fba leads to the positive behavior plan. This plan is not to eliminate behavior only, it is to teach skills so the child does not have to use the negative behaviors.
---how many days total are you up to after this. The district has 10 days to suspend if he is on an IEP for a pattern of behaviors...and then they must do a manifestation determiation. This will say if the behaviors are related to his disability. (usually obviously yes) and then they need to say, well then, the IEP and BIP is not good enough, his needs are not being met if this stuff is continuing. They must look at how to change it, accomodations, interventions, reinforcements, etc.
----they may say they can not meet his needs in that setting. Make sure you have an advocate. This can get sticky and you dont want him shoved somewhere just for their convenience. IF there really is a better setting that is one thing. If they just put all the kids wth behaviors in one place, that is quite another.
If they are stupid enough to use up the 10 days then it is their dumb decision. The principal is wrong to say he has to be held to the school conduct code, you can amend his IEP to even reinforce this. I have in my sons IEP that due to Q's autism and acquired brain injury, he is unable to follow school and district conduct code as written. All discipline decisions will include the special educaiton team.
I have to say, spitting is my red hot button, where I can really lose my temper with my son. But the fact is it is not serious bodily harm. a 3 day supension is going to do what exactly? He probably likes the days off, it punishes you, increases stress and anxiety in the home, and if he does hate it, it will make him more nervous about getting in trouble--then making it harder to behave. Any administrator that thinks this makes a difference does not read the research. IEP's are supposed to use evidence based methods, and suspension is evidence based to NOT work. They do it to make the appearance of doing something and being in charge. IN fact it makes nothing change. IF it would work, I am guessing he would have been "fixed" long ago right??? Maybe the first 2 or 3 times he was suspended. DUH. It makes me absolutely insane.