If a judge in China gets told to do something by someone above him in the CPC the judge will write a plausible or not so plausible legal opinion justifying what they were told to do. There is unlikely to be any explicit paper trail and from the outside you might confuse the Potemkin legal system for that of a Rechtstaat, where the government is, at least theoretically, bound by laws. In the US or Canada the government can interfere in the judicial process for reasons of national security and that’s really it. If Trump, Obama, Bush, Clinton or any of the others called up a Supreme Court Justice and tried to tell them what to do they’d get told, politely or not, to go take a running jump. The government’s lawyers can make an application for evidence to be sealed from public view if it’s classified, or they can ask that a prosecution be aborted for reasons of national security.

The big difference is that things do not work on the basis of discretion or chain of command. If the sub mayor of Baoshan District Shanghai tells a police officer to cover up a murder or charge a foreigner with drugs offences because they broke up with the sub mayor’s daughter it will happen. If Trump tries to shut down the Huawei investigation for national security reasons the court could listen to his justifications and say no.