This story happened to a friend of mine whom we shall name Yitzchak:
Yitzchak was travelling on an intercity bus one night, when three Arab labourers boarded. Apparently fearing for their safety, one of the passengers called the police. Three cops came to check whether the Arabs had entry permits or not. Since one of the Arabs appeared to be sleeping, a mean-looking cop roughly shoved the Arab’s head back demanding his papers. Upon seeing this, Yitzchak arose and loudly accused the cop of disgracing his government uniform, demanding the cop’s badge serial number and other details. “But he was only feigning sleep”, the cop tried to explain. Yitzchak would have none of it. “And what if he was? He’s a person, is he not?! This will end up in Machash (the Israeli version of Internal Affairs)!”
Once the bus had resumed its route, another traveller, a Gerrer Chassid, turned to Yitzchak and said: “I see you are an Arab-lover…” Yitzchak replied, this time calmly: “This is not about the Arab at all. Tomorrow you and I could be at a demonstration protesting the desecration of Shabbos or the like and this same cop, having been given free reign once, could assault either of us, as well. What will you say then?” The Chassid had to agree.
And no, it didn’t end up in Machash…
By the way, to lodge a complaint against a policeman, see this guide.