Do to the latest heat wave here in northern Ca, I was i'll this last Sunday and Monday and couldn't go to work. I called in to work 3hrs before my shift, that way they had plenty of time to cover me. Business policy is 2hrs, before start of shift. Today my boss informs me that they are starting a new policy No more than 2 sick days per quarter. Then hands me a write-up and informs me that if I call in sick again I can be fired. I told my boss, I talked to my doctor and was getting a medical note for her, I was informed it doesn't matter. Can you get write-ups when you don't know the rules the company has started to go by? Do doctors notes matter or not? The 2 other times i've been off sick this year, were 2 days each and I had a doctors note then too. Thanks for your help.

Unless your absence is qualified under intermittent FMLA, there is no job protection for being sick.

Do to the latest heat wave here in northern Ca, I was i'll this last Sunday and Monday and couldn't go to work. I called in to work 3hrs before my shift, that way they had plenty of time to cover me. Business policy is 2hrs, before start of shift. Today my boss informs me that they are starting a new policy No more than 2 sick days per quarter. Then hands me a write-up and informs me that if I call in sick again I can be fired. I told my boss, I talked to my doctor and was getting a medical note for her, I was informed it doesn't matter. Can you get write-ups when you don't know the rules the company has started to go by? Do doctors notes matter or not? The 2 other times i've been off sick this year, were 2 days each and I had a doctors note then too. Thanks for your help.
I am afraid that doctors notes do not help you if they want to fire you. Only in an instant, like FMLA, would a doctors note help. You are in an at will state, which means that your boss could fire you for anything (like your hair color), as long as it does not fall in the discrimination catagory, like age, sex, religion etc. I am not a lawyer, so someone may know something different, so be patient, someone will come along. I would ask though, that the write up be taken off your permanent record, since they informed you of the policy change AS they were handing you the write-up.

Sorry but unless FMLA applies, the doctor's note is irrelevant. Feeling ill due to the heat would not cut it under FMLA. It may be unfair that you were written up for violating a rule you didn't know about, but it is legal.