If the prosecution has no case, you don't spent years lobbying the government to create a DPA law, then demand a DPA once the law is established.
If the prosecution has no case, you don't accept a guilty plea.
If the prosecution has no case, you say "You have no case, we will fight these charges in court."
SNC-Lavalin had 280 million reasons to reject this plea agreement. So once again:
If the prosecution had no case, why did SNC-Lavalin agree to plead guilty and pay $280 million in fines?
If the prosecution had no case, why did SNC-Lavalin agree to plead guilty and pay $280 million in fines?
If the prosecution had no case, why did SNC-Lavalin agree to plead guilty and pay $280 million in fines?
Posted in big boldface letters so that you can't miss the question and everybody else can see that you keep ducking it.
$280 million in fines is a hell of a lot more impacting than a "not guilty" verdict! Why didn't they fight the charges in court? Huh? Huh?
ok, I've let you have enough rope now!

Notwithstanding I've never offered comment on whether there was 'ACase', how are you expecting anyone from the general public to know just 'WhatCase' the PPSC had... or didn't have? As I recall, the only thing I've stated is that legal analysts suggested PPSC might have difficulty in proving... WhateverCaseTheyMightHave! And why? As I stated, because of the datedness of the alleged crimes, the foreign element, the death/absence of many of the key players {allegedly} involved, etc..
what I've also stated, several times, is that the Director of PPSC was quite emphatic in stipulating the key reason behind her decision not to offer a DPA - as she stated, her principal reason for not offering a DPA to SNC-L was due to the, “
nature and gravity” of SNC-Lavalin‘s alleged corruption in Libya. That's quite precise... specific... defined! It reads like the PPSC sure envisioned they had TheGoods to support conviction - must have been quite TheCase to render said decision, hey member kimmy?
what you can't answer, what you keep deflecting away from, is the simple question: if PPSC had TheGoods, had TheCase, why did it withdraw all 6 charges of fraud and corruption (3 and 3), and instead had SNC-Lavalin accept a guilty plea on one charge of fraud over $5000? If only you could focus and offer an answer - if only! 
you're also under some strange and unfounded understanding that a defendant is fully aware of what evidence... what proof... what case, a prosecution has to support a presumed conviction. Of course, as you're also clearly unaware, a typical key stipulation of DPA's has a defendant admit quilt and assist prosecution in providing all manner of available information to align with and prove/support said guilt!