Is it acceptable for the police to violate a persons rights without any checks?

I know someone who was doing nothing wrong at the time he was stopped by police. He was stoppped(really) for being in the wrong place in the normal course of his day. The police charged him with providing false information to the officer which is untrue. They did not read him his rights at any point. Another day he was given tickets for an accident that occured. The police are calling him the driver, based solely on the real drivers testimony. No property was damaged, the accused had the only injuries(proven by the 5 times over shattered windsheild on the passenger side, paired with his neck/head injuries.)

He has no money for a real lawer and was frightened into pleading guilty to the first offence even though he didn't do it. How can we do damage control and get out of the other rediculous charge??

Additional info. The public defenders are overworked and unable/unwilling to work that much. The appointed defender said tough luck...they know about that officer, but watcha gonna do...basicaly. He wants to file an appeal but is afraid of loosing and suffering a worse sentance than the deal the state offered.

The thing with the accident lacks proof, but it was in the same county, and he fears getting railroaded again. It has yet to go to the judge for that yet(next week)

He has the right to an attorney, whether he can afford one or not.
He can ask for a public defender at his arraignment.
If he was not read his rights after being arrested, any statements made to the police can be challenged and possibly suppressed by his attorney.
I really couldn't answer the rest of your question without knowing all of the facts.