In China, police control of street protests can be accomplished under existing law both directly, through administrative penalties including detention that police can impose on their own authority, and indirectly, through the threat of detention as part of the ordinary criminal process. In the ordinary criminal process Chinese law provides police and prosecutors extensive discretionary authority to detain suspects and defendants for periods of six months or more without judicial review. While the structure of these detention provisions superficially resembles that in Western countries, their operation is wholly subject to internal policies and practices of police and prosecutors. In addition to providing an overview of these provisions, we review here a recent prosecutorial policy change in decision-making on extended detention (dàibǔ, 逮捕) that places the same prosecutor in charge of both this decision and the ultimate presentation of the case. We conclude that this may encourage individual prosecutors to assess their cases more thoroughly and realistically at an earlier stage and may alter the litigation dynamics of detention during the investigative phase, but it does not reduce the threat of detention as a means of deterring protests. At most, the change may provide negotiation opportunities for defence counsel. Until a Chinese criminal case is formally presented to a court, control over detainees remains firmly in the hands of the police and prosecutors.