And for each potential charge, there’s the legal requirements, and the evidential one.
Suppose you have a potential offence that has three elements: prosecution must prove elements A, B and C for there to be a conviction.
So there’s the legal research: what have the courts said is necessary to prove A, B and C? How clear-cut are the precedents to tell you what you need for each element? What kind of evidence have the courts accepted in the past, and what have they rejected?
Then the prosecutors have to ask themselves, “Do we have evidence to prove each element?”
Maybe they conclude that the documents they have are solid to prove element A, and they’ve got three or four witnesses that are good for element B, but they’ve only got one witnesses that can provide evidence on element C.
They have to do their own assessment of that witness. How strong is that witness? Are there weaknesses in what the witness can testify to? Is there any reason to doubt the testimony ? Will the witness be really vulnerable on cross ? Is it worth going to trial depending largely on the testimony of one key witness? That kind of assessment takes sound professional judgment based on the individual prosecutor’s experience in court.
And, are there questions about the admissibility of the evidence? Even if the documents are solid for element A, is there any question about their admissibility, under the rules of evidence? Is there a constitutional issue about how they were obtained?
And even if the prosecutors conclude that all their witnesses can testify to all the elements of the offence, there’s the final overall standard: is there a reasonable likelihood of conviction? (This test is phrased differently in different jurisdictions, but that’s how it’s commonly expressed.) It’s an overall assessment, taking all the evidence into account, and weighing it against the legal standards the courts have developed for that charge.
Is the potential charge or legal theory an unusual one? Assault with a weapon is a very common charge and won’t take as much detailed research or assessment. Most prosecutors start their career with common charges like that, and there’s ample case-law to tell you what you need. But if it’s an unusual charge, unusual facts, with offences that aren’t charged very often? That assessment of reasonable likelihood can be quite difficult.
But that test is a necessary step in the exercise of prosecutorial discretion. We don’t want the state bringing charges that have no reasonable likelihood of conviction, because that would be an abuse of the state’s power. Meritless prosecutions of an individual are a misuse of the prosecutions power. Charging a citizen with a serious criminal charge can drag them through the wringer, emotionally, financially, and socially. A charge should only be laid if it meets that standard of a reasonable likelihood of conviction. You don’t just bring five charges and see if any stick, on spec.
Now rinse and repeat for the next potential charge, and the next.
Sure, more resources help, but these are all necessary steps, particularly for complicated charges. And, we don’t want to rush them, because that can contribute to obvious mistakes.
To put it in a different context: if you’re researching an academic issue for a book you want to write, more resources help, like support staff, research grants, maybe a sabbatical to focus on the writing. But, there is an irreducible minimum of work that you need to do yourself, correct? That you have to research before you can write, and that you then have to write and re-write to meet the high academic standards for a sound reputation? Maybe have a trusted colleague read the draft for critical commentary?
Bringing charges, particularly in a complex case, is like that. There is an irreducible minimum of work that must be done, and takes time, no matter the resources.