The Toronto Star has been running a series on the mathoms of Canadian police forces and their effects on Police Background Checks done to see if you can have a civilised job or not. Three sets of circumstances arise.
You hold up a bank, firing wildly into the crowd as lead the police on a merry chase during your getaway. You are caught, tried and convicted. You serve your time, ponder the error of your ways, pay your debt to society and are eventually released. After a certain time has passed you may apply for a pardon and all records of your escapades are erased. You may now re-enter society and aspire to climb to any height through honesty toil.
Or, you get into a nasty court battle with your psycho, pathological liar boyfriend. The court determines that his accusations of you threatening him are baseless and were simply an attempt to divert the court's attention from his constantly turning your face into hamburger through vicious beatings. You are officially acquitted of all charges and he goes to the slammer for 10 years: eventually to be pardoned - see above. You, however, will never be able to pass a Police Background Check because you are listed in the "pieces of tattle and gossip" national database as having "been accused of assault". There is no procedure for ever erasing anything from this and it is promiscuously shared with every police force, secret or otherwise, on the planet. It would be unwise to attempt any border crossings and of course you can kiss any ideas of being a nurse or fire fighter good bye forever.
Equally disabling is the case where a neighbour has a few mooney martoonies and phones the police that to say that you are a KGB spy. The cops show up and throw his ass in jail for being drunk and filing a false report. However the false report is now in the national gossip database so see above for the effects on your ability to earn a living. Even better, since you were never in contact with the police or made aware of this incident at all you might spent a few thousand on a training course before trying the, doubtless perfunctory, step of doing the background check. Ha ha! Jokes on you.
Each case is illustrated with a real-life example.
Of course no one is ever put on the lists because they annoyed a rich person...