Discription of Events: We were both in the left lane on i10 W coming into tucson, she was in front of me and started to purposely going under the speed limit and then started to brake check me to purposely cause an accident for no reason. I never tried to pass her because there was a semi in the right lane next to us. Clearly there was no one in front of her either, so I was very scared and backed off until my exit. The aggression of how hard she hit the brakes was shocking, as this has never happened to me before. Road rage at its finest, be safe.