So What Really Happens
to turn Sammy Suspect into Danny Defendant? The short answer is that the cops convince the reviewing APA that s/he should authorize the issuance of an arrest warrant. The long answer follows.
There are, in practice, a number of different standards that can be used to determine whether a warrant should be authorized. They boil down to three, in my experience. The lowest, and the one I've never heard of being the official policy of any of the offices I'm familiar with, is probable cause. Probable cause is the standard applied by the judicial officer who issues the warrant once it has been authorized by the prosecutor. It would seem logical to use the same standard, more or less, for authorization in the first place, you'd think. But it's really not.
Most of the time, when a felony warrant request hits the desk of some lucky APA it's an indication that the police think the investigation is complete. There are, obviously, exceptions. But for the run of the mill felony, e. g. a breaking and entering or a serious assault, when the warrant request is submitted, the police don't expect to do much more than serve the warrant and any subsequent subpoenas for court proceedings. This belief is not always shared by the reviewing APA.
Sometimes the problems are minor administrative or clerical glitches like an incomplete witness list or a missing criminal history. Sometimes they are major administrative or clerical hitches like a missing report from an other officer or an assisting agency. And sometimes they are just plain screwed up. Examples of the last category are eye witnesses who were not interviewed, controlled substances with no weight, or stolen property with no description or value.
If the standard for authorization is only probable cause, the same probable cause that justifies an officer in making an arrest, then it is more than likely that warrants could be (hell, would be) authorized before the investigation is complete. And an authorized warrant most generally rings the final bell on any run of the mill investigation.
Don't misunderstand me on that. I'm not saying there is never any follow-up investigation once an APA puts her Joan Hancock on a warrant authorization. There often is. Serious felonies like murder, rape, large scale theft/embezzlement, major weight drug offenses, and the like are going to involve active investigations right up to the time the judge charges the jury. But a B and E of a store, a low grade concealed weapons charge, minor drug possession, petty theft and similar property crimes are not likely to inspire CSI-like investigative efforts. There is a lot of crime out there, and a limited number of police officers to investigate it. Add in local idiocies like a major department that does not allow uniformed officers to do any investigation beyond the immediate incident report, and you have a serious, on going resource allocation problem. This is just a fact of life for police supervisors and prosecutors alike.
So what does a canny boss prosecutor do to minimize the number of cases that are authorized without sufficient investigation? He institutes a policy of only authorizing cases that, at the time of authorization, in the opinion of the authorizing APA, can be proved to a jury beyond a reasonable doubt. The way our charging policy explains this is by directing the screening APAs to ask themselves this question: If you were to take this case, as it now exists, with the testimony of the witnesses, and the other evidence, conforming to what is represented in the police report, could you prove this case to a jury, beyond a reasonable doubt? If the answer is "yes" authorize the warrant. If the answer is "no" why is it "no" and what needs to be done to change the answer to "yes?"
When the answer is, in fact, "no" the reviewing APA writes a detailed note on the request to charge, explaining just what she thinks is necessary to get to "yes" and returns the package to the requesting agency.