The agents who installed the criminal tracking device and interpreted (doctored) the data, were in the courtroom and smiled broadly at Jim's futile challenge of conventional wisdom.
It is possible that there was no device and the whole rig was made up in the narc lab, using physical tailing as the source of info needed to confect digital, ie, neutral, evidence. This follows, naturally, the fact that agents' testimony is not believed by anyone any more, so often do they lie.
"In the halls of justice, the only justice is in the halls.
-- Lenny Bruce
