Last time I served on a jury, the judge gave the same instruction regarding police as witnesses. Nevertheless, the defendant had a heavy accent, and did not testify in her defense. The prosecution presented their entire case through the testimony of one policeman, who was shown to be wildly exaggerating to the point of an outright lie in a key element of his testimony. He never recanted or even corrected his testimony. Yet the first vote was massively in favor of convicting. Scary!