Can An Expert Be Sued For An Error or An Omission?
A Professional, As a Trained Expert That Is Relied Upon For Quality Advice or Opinion May Be Legally Responsible For Unreasonable Mistakes That Result In Harm. A Qualified Expert Witness May Be Required For Confirming What Was Unreasonable.
Understanding What Constitutes As Professional Negligence Involving An Error, Omission, or Malpractice, Incident
Professional consultants and advisors, such as an architect, an engineer, a surveyor, an inspector, an insurance broker, a financial planner, a designer, a lawyer, an accountant, a doctor, an other type of medical practitioner, among many others, are imperfect just the same as everybody; however, when a professional makes a mistake, the error or omission may result in death or injury, damage to property, serious financial impact, or sometimes even a combination of these consequences. Of course, the type of professional can vary and thus the harm that results from a mistake also varies depending on the type of professional involved; a mistake by a doctor may cause death or injury; a mistake by an engineer may cause a bridge to collapse involving property damage as well as death and injury, and a mistake by an accountant could cause tax reassessments resulting in retroactive interest due among other monetary losses.
Standard of Care in Conduct
Professionals in a particular field are expected to perform services with a due diligence and reasonable extent of expertise; however, like the law applicable to all concerns involving alleged negligence, professionals are without a duty to perform perfectly; and instead, professionals must only perform reasonably within the circumstances. This requirement of reasonableness rather than perfection was stated by the Supreme Court within the case of Hill v. Hamilton-Wentworth Regional Police Services Board,  3 SCR 129 where it was said:
73 I conclude that the appropriate standard of care is the overarching standard of a reasonable police officer in similar circumstances. This standard should be applied in a manner that gives due recognition to the discretion inherent in police investigation. Like other professionals, police officers are entitled to exercise their discretion as they see fit, provided that they stay within the bounds of reasonableness. The standard of care is not breached because a police officer exercises his or her discretion in a manner other than that deemed optimal by the reviewing court. A number of choices may be open to a police officer investigating a crime, all of which may fall within the range of reasonableness. So long as discretion is exercised within this range, the standard of care is not breached. The standard is not perfection, or even the optimum, judged from the vantage of hindsight. It is that of a reasonable officer, judged in the circumstances prevailing at the time the decision was made — circumstances that may include urgency and deficiencies of information. The law of negligence does not require perfection of professionals; nor does it guarantee desired results (Klar, at p. 359). Rather, it accepts that police officers, like other professionals, may make minor errors or errors in judgment which cause unfortunate results, without breaching the standard of care. The law distinguishes between unreasonable mistakes breaching the standard of care and mere “errors in judgment” which any reasonable professional might have made and therefore, which do not breach the standard of care. (See Lapointe v. Hôpital Le Gardeur, 1992 CanLII 119 (SCC),  1 S.C.R. 351; Folland v. Reardon (2005), 2005 CanLII 1403 (ON CA), 74 O.R. (3d) 688 (C.A.); Klar, at p. 359.)
Recently, within the case of Formosa v. Persaud, 2020 ONCA 368, while citing the Supreme Court in Hill, the Court of Appeal reiterated that minor errors or errors in judgment may occur, and produce unfortunate results, without rising to the level of negligence. Specifically, the Court of Appeal stated:
 The appellants complain that GR made errors in judgment. However, as stated by McLachlin C.J. in Hill v. Hamilton-Wentworth Regional Municipal Police, 2007 SCC 41,  3 S.C.R. 129, at para. 73, the law of negligence accepts that professionals may make minor errors or errors in judgment that cause unfortunate results, without breaching the standard of care. Here, the motion judge found that the appellants were advised of the risks in litigation generally and in the TIG action specifically. His findings were fully supported by the record. Moreover, there is no dispute that the litigation strategy was to be aggressive with a view to motivating TIG to settle. We are fully satisfied of the merits of the motion judge’s findings.
Required Evidence, expert opinion report
In most circumstances, the opinion of a subject expert will be required to demonstrate that the standard of care was breached by the professional unless the allegations of professional negligence relate to a non-technical or egregious error. This was stated within, among others, the cases of Guindon v. Dolson, 2012 ONSC 1968 as well as Ronald Gunraj v. Chris Cyr, 2012 ONSC 1609 wherein it was said:
 Mr. Bennett, counsel for Mr. Dolson, ably argued that the lack of expert evidence in this case is fatal to the Claim. I agree. Expert evidence is required to establish the requisite standard of care in professional negligence cases, including those against lawyers, except in (i) extraordinary cases involving non-technical matters or (ii) cases involving plainly egregious conduct. This Court draws that conclusion on the authority of jurisprudence from the Court of Appeal for Ontario including the decisions in Gauvreau v. Paci, 1996 CarswellOnt 2661 and Krawchuk v. Scherbak, 2011 CarswellOnt 3015.
 The jurisprudence indicates that, in general, it is inappropriate for a trial court to determine the standard of care in a professional negligence case in the absence of expert evidence. There are two exceptions. The first is cases in which it is possible to reliably determine the standard of care without the assistance of expert evidence, because the court is faced with "non-technical matters or those of which an ordinary person may be expected to have knowledge.” The second is cases in which the impugned actions of the defendant are so egregious that it is obvious that his or her conduct has fallen short of the standard of care, even without precisely knowing the parameters of that standard. Nevertheless, even in cases like 1041590 Ontario Limited v. Camley Investments Inc., in which the motions judge concluded that expert evidence was not strictly required, the matter ought not to proceed to trial where the summary judgment respondent has failed to provide virtually any standard of care evidence.
As above, there are also cases where the error or omission is plain and obvious and more a basic function of the professional rather than a function that requires a technical analysis and understanding of various aspects of the professional service. Accordingly, mistakes such as basic adminstrative errors may be accepted by the court without requiring expert testimony that such mistakes breach the standard of care. This was stated well in Hill v. Queensbury Strategies Inc., 2014 CanLII 45416 at page 16, where it is said:
Considering the unique evidence and facts of this case, I do not need expert evidence to conclude that Skakie was negligent and in breach of the standard of care applicable to registered mutual fund sales representatives. His actions do not involve technical and complex details of the mutual fund industry for which I need assistance in determining whether there was a breach of the standard of care. He breached the standard of care in the following ways:
(a) he was told by the Plaintiff to change her mailing address but never took the steps necessary to ensure that the address was changed in the company records;
(b) he failed to take the steps necessary to ensure the Plaintiff understood at all material times the amount of B2B loans, understood the interest rate being charged, and understood the actual position of her account in terms of whether she was in a profit or loss position;
(c) he failed to obtain correct information on the B2B interest rate when opening the account;
(d) he failed to ensure that the Plaintiff understood how the monthly payments were reduced to $150.00. He failed to ensure that the Plaintiff understood that there was not an adjustment of interest rate, but rather a reduction in the principle of the loan;
(e) he never took the steps necessary to ensure that the Plaintiff had internet access to her account.
Causation Requires Connection
After the Plaintiff meets the burden of proving that the professional failed to meet the proper standard of care, proof of causation of loss follows the 'but for' test. This was simply stated in Hill at page 20 as:
Causation is determined after the court has found a breach of a duty of care. The basic test for determining causation remains the “but for” test – the plaintiff must show on the balance of probabilities that, but for the negligence of the defendant, the injury would not have occurred. This requirement for a causal connection ensures that liability arises only where the harm suffered only occurred due to the mistake. If the harm was inevitable regardless, liability for the mistake fails to arise.
Actual Case Examples Involving Various Professionals
Just as there are many types of professionals whose mistakes could cause harm or injury, there are many actual examples including the cases as brought against:
Errors & Omissions Cases Against Property Inspection Services
- Rimmer v. Building Insights Inc., 2013 ONSC 5561
- Salgado v. Toth, 2009 BCSC 1515
- Semeniuk v. Key Home Inspections Ltd., 2013 ABPC 254
Errors & Omissions Cases Against Insurance Agents or Broker
- Fine's Flowers Ltd., et al v. General Accident Assurance Co., 1977 CanLII 1182
- Fletcher v. Manitoba Public Insurance Co.,  3 S.C.R. 191
- Canada Brokerlink Inc. v. Patterson, 2006 CanLII 50894
Errors & Omissions Cases Against Legal Advisors (lawyers or paralegals)
- Guindon v. Dolson, 2012 ONSC 1968
Errors & Omissions Cases Against Financial Planners
- Hill v. Queensbury Strategies Inc., 2014 CanLII 45416
Professionals who are relied upon for advice and opinions may be held liable for errors or omissions, among other mistakes that cause harm as a result of the failure to render the professional services in a reasonably competent manner. Expert witness input as to what constitutes the reasonable standard experted of a similar expert will be highly important evidence within such a legal case.