In the future it would appear that a great number of police officers are women, in Hill Valley at least. The residents are more comfortable being questioned by women than by men.
In Back to the Future, we can follow two Hill Valley Police officers, Reese and Foley, for a few moments. A little screen on their caps displays their names. The message "MY NAME IS OFFICER FOLEY" can be read at the McFlys.
Foley and Reese don't appear to bear any firearms, but the ease with which Doc tranquilizes Jennifer suggests that future technologies have created weapons well in advance of those used by police today.
Truncheons, on the other hand, are still used in 2015. The two agents bear them at all times, especially in a rough neighbourhood like Hilldale. The fluorescent glow of the truncheons, rendering them visible at night, dissuades potential trouble makers from tangling with the agents, who are themselves made very prominent in the dark.
To stay in touch with police headquarters, the officers of the future wear transmitters on their wrists allowing easy communication.
Finally, Hill Valley's continuous expansion necessitates rapid movement throughout the town. To uphold the law, the police patrols are equipped with a technological gem. It's a flying vehicle; allegedly the latest advance in hover technologies.
Other officers use vehicles that look like large motorbikes. These arrive rapidly at the Town Hall that Griff and his gang have wrecked.
In the movie we witness a police check carried out on Jennifer, who is then heavily tranked. Using her finger prints, the officers yield the following information:
Her criminal record is blank, so the officers decide to take her back to her home address.
This implies that they have the power to take repeat offenders into custody.
The justice system is the only thing that seems to have degraded with time. In order to speed up the legal process, and certainely reduce its cost, lawyers have been done away with.
How do you defend yourself then ?
Added to this, the lack of time makes it impossible to gather the evidence and witnesses required to mount an effective defense.
Sentences are passed rapidly. The paper informs us that two hours after his arrest, Marty McFly Junior has been found guilty and condemned to 15 years for armed robbery. Further on, Marlene gets twenty years for trying to help her brother escape !
These sentences are the product of cold computer logic. Marty and Marlene have simply been handed the maximum penalties permissible under the law.
Poor Marty, beaten up by Griffs gang, was forced to take part in the break in. "I'll do whatever you say" he says after being hurled behind the Cafe 80s Bar. Fifteen years without parole for a crime you didn't want to commit is very unjust, and for a minor at that ("Youth jailed" reads the newspaper headline).
One fears for Griff and his gang.