The Supreme Court of Canada has established the requirements for a bail review in numerous decisions – notably, St-Cloud and more recently in Myers.
The Alberta Court of Appeal, however, has decided to limit the value of a bail review to an accused person: R v Ledesma, 2019 ABCA 60 (CanLII). Reading carefully, it refers specifically to a subsequent bail review application – not a first bail review application (e.g. denial at provincial court and then review at a superior court) [Nov. 1, 2019 edit: this last point is not technically accurate, but the cases it quotes are mostly subsequent bail reviews. More importantly, its damaging comments are all obiter dicta – see paras. 43-45]. Regardless, it appears to limit the availability of a “change in circumstances” argument to a “significant” change – preferably one that one was simply not available on the initial bail application. It is likely to mislead courts into thinking the change in circumstances argument is now restricted in this way (at least in Alberta) – whether or not this was an intended consequence of the decision:
See paras. 33-35:
 To be clear, however, second or subsequent bail applications must not be seen to be a forum at which a previously disappointed applicant seeks a fresh judge’s exercise of judicial discretion, or a redetermination of findings of fact made on the initial review: R v Sarancino, 1989 CanLII 7197 (ON SC),  OJ No 28 at para 18, 47 CCC (3d) 185 (Sup Ct). Abuse of forum-shopping is avoided if subsequent bail applications are restricted to cases where there is a significant change in circumstances and “not just an attempt for a second or further bite at the apple”: Seti-Mayinga at para 31.
 In our view, moreover, a change of strategy does not amount to a change of circumstances. Rather, an applicant for bail is obliged to put his or her best foot forward at the original hearing. Put another way, the original bail hearing is not a consequence-free opportunity to simply “test the waters” and if bail is refused on the basis of the applicant’s initial plan, then it is time to “up the ante” in subsequent applications, and offer other options that were known to the applicant at the original applicant [sic], and which may have been less convenient, more expensive, or more restrictive.
 A bail applicant is well advised not to treat the original bail application or any subsequent bail application as a form of fluid, malleable, ongoing negotiation or debate with the court, that will somehow permit the applicant to hold in reserve known but less preferred release options, on the theory that if the original bail hearing is unsuccessful, then the less preferred options can be offered up to the court the next time around, or perhaps the time after that. This dicta applies both in the present context of a severely over-taxed Alberta court system, and otherwise in the event that that situation improves.
The damage is partially mitigated in para. 41:
 In the latter situation, where the accused has recently been charged, remanded into custody and wishes to be released as quickly as possible thereafter, it may be unreasonable and unfair to preclude adducing any additional evidence at a subsequent application. In such a situation, the applicant’s counsel may need additional time to analyze and weigh the advantages and disadvantages of using evidence of alternate available release options. But, the applicant’s need to show the original bail judge a reason that is legitimate and reasonable, means new evidence will not be admitted where the accused person wishes to “drag out the application for release” or where the accused is attempting “to engage in judge-shopping”: St-Cloud at paras 125, 127, 133-134. It is the former situation with which we are concerned in the case at bar.
See, however, paras. 131-134 of R. v. St-Cloud, 2015 SCC 27:
 Moreover, despite the importance of these values, this Court has also stated that the due diligence criterion should not be applied as strictly in criminal matters as in civil cases: Palmer, at p. 775, quoting McMartin v. The Queen, 1964 CanLII 43 (SCC),  S.C.R. 484, at p. 493. The weight to be given to this criterion depends on the strength of the other criteria or, in other words, on the totality of the circumstances: R. v. Price, 1993 CanLII 76 (SCC),  3 S.C.R. 633, at p. 634; see also Warsing, at para. 51. In G.D.B., this Court stated that “an appellate court should determine the reason why the evidence was not available at the trial”: para. 20. A generous and liberal interpretation of the meaning of “new evidence” in the context of ss. 520 and 521 Cr. C. is thus quite consistent with the principles developed by this Court.
 I am therefore of the opinion that a reviewing judge may consider evidence that is truly new or evidence that existed at the time of the initial release hearing but was not tendered for some reason that is legitimate and reasonable. This is how the “due diligence” criterion from Palmer must be understood in the context of the review provided for in ss. 520 and 521 Cr. C. The nature of the release system and the risks associated with it demand no less.
 I wish to be clear that such new evidence is not limited to evidence that was unavailable to the accused before the initial hearing because, for example, the prosecutor did not disclose it to the accused. It is possible that the prosecutor will give the evidence to the accused only at the very last minute before, or very shortly before, the initial hearing. Depending on the circumstances of a given case, it could be unreasonable and unfair to say that if the accused does not use such evidence at the initial hearing, he or she will be precluded from adducing it on a subsequent application for review, that is, after his or her counsel has had the necessary time to analyze it and weigh the advantages and disadvantages of using it. In each case, the reviewing judge will have to determine whether the reason why the accused did not tender such pre-existing evidence earlier was legitimate and reasonable.
 This requirement to show a reason that was legitimate and reasonable means that it will be open to the reviewing judge to refuse to admit new evidence where it is alleged to have actually been in the interest of the accused to drag out the application for release or where the accused is alleged to have tried to use the review to engage in judge shopping. In this way, the conception of new evidence in the context of ss. 520 and 521 Cr. C. reflects both the need to ensure the integrity of our criminal justice system and the need to protect the rights of accused persons in proceedings that are generally expeditious.
In R. v. Myers, 2019 SCC 18 (in the context of a s. 525 – or “90 day” review, whereas typical bail reviews are under sections 520 or 521), the Supreme Court of Canada re-affirms the test set out in St-Cloud, and clarifies that a change in circumstances is defined rather generously:
 Furthermore, both parties are entitled to make submissions on the basis of any additional “credible or trustworthy” information which is relevant or material to the judge’s analysis. The admissibility of any material that existed at the time of the initial bail hearing but was not presented at that point should also be governed by the criteria of due diligence and relevance discussed in St-Cloud, at paras. 130-35. In the context of a s. 525 review, the judge must be particularly attentive to any new evidence or material change in the circumstances of the accused and to its impact on the question whether his or her continued detention in custody is justified. For example, the period of pre-trial detention may have afforded the accused person time to make arrangements for a suitable surety, develop a comprehensive release plan or take other steps that would negate the initial basis for his or her detention under s. 515(10). [Emphasis added.]
I’d like to think that Ledesma will not be used to limit the ability of an Accused to argue a change in circumstances – particularly in the context of a first s. 520 review, given the Supreme Court’s pronouncements in St-Cloud and Myers.