In opposed motions, many arguments masquerade as affidavits. This is improper. For the most part, legal argument should be confined to factums.
In Ferreira v. Cardenas, 2014 ONSC 7119, Justice Myers eloquently sets out the rules on affidavits sworn in support of motions:
 Lawyers’ affidavits can be quite helpful in cases where the lawyers, or their staff, have particular knowledge relevant to the facts in issue before the court. In Mapletoft v. Christopher J. Service, 2008 CanLII 6935 (ON SC) at para. 15, Master MacLeod provided the following guidelines for the use of lawyers’ affidavits:
- For the guidance of counsel in future, I propose the following guidelines:
a) A partner or associate lawyer or a member of the clerical staff may swear an affidavit identifying productions, answers to undertakingsor answers given on discovery. These are simple matters of record, part of the discovery and admissible on a motion pursuant to Rule 39.04. Strictly speaking an affidavit may not be necessary but it may be convenient for the purpose of organizing and identifying the key portions of the evidence. Used in this way, the affidavit would be non-contentious.
b) If it is necessary to rely on the information or belief of counsel with carriage of the file, it is preferable for counsel to swear the affidavit and have other counsel argue the motion. This approach will not be appropriate for highly contentious issues that may form part of the evidence at trial. If the evidence of counsel becomes necessary for trial on a contentious issue, it may be necessary for the client to retain another law firm.
c) Unless the evidence of a lawyer is being tendered as expert testimony on the motion, it is not appropriate for an affidavit to contain legal opinions or argument. Those should be reserved for the factum.
 Some procedural motions turn on evidence that counsel is uniquely situated to provide. For example, a motion for dismissal for delay under rule 24.01 or a motion to amend a timetable under rule 3.04 will turn on facts concerning how the litigation has progressed or the reasons why it may not have progressed for a period of time. Counsel, rather than clients, are often best suited to have personal knowledge of these types of facts. Similarly, if the conduct of counsel is the subject matter of a proceeding, such as a motion for costs under rule 57.07 or more a motion brought to compel undertakings under rule 34.15, then, once again, counsel will likely be best suited to provide firsthand evidence of relevant facts.
 It is rarer for law firm clerical staff to be helpful witnesses. In some cases, a clerk or assistant may conveniently adduce evidence simply exhibiting correspondence between lawyers that is non-contentious. By contrast, evidence from a lawyer adduced by way of information and belief through a staff member simply limits the weight of the evidence and should be discouraged: Essa (Township) v. Guergis; Membery v. Hill, 1993 CanLII 8756 (ON SCDC),  O.J. No. 2581 (Ont. Div. Ct.). Moreover, this is not an appropriate vehicle if the lawyer who provides the information wishes to be counsel at the hearing: Manraj v. Bour, 1995 CarswellOnt 1335 (SCJ). One may also question the advisability and propriety of exposing administrative staff to cross-examination.
 Unlike these procedural motions, motions for summary judgment go to the heart of the merits of the dispute between the clients. The lawyers for the parties generally have no firsthand knowledge of the facts. They have no “specific facts showing that there is a genuine issue requiring a trial”. For this reason, information and belief evidence tendered through a lawyer’s affidavit will rarely satisfy rule 20.02. Moreover, as the Court of Appeal explained in Armstrong v. McCall, 2006 CanLII 1748 at para. 33, there is a concern that information and belief evidence will be used to shield persons from cross-examination.
 Lawyer’s affidavits that recite background gleaned from “the file” are especially problematic. Although affidavits based on information and belief that fail to state the source of the information are not struck out automatically (see Carevest Capital Inc. v. North Tech Electronics Ltd. 2010 ONSC 1290(CanLII) at para. 16), one doubts whether these vague “advised by the file” affidavits are proper information and belief evidence at all or whether they really just serve to put the affiant lawyer’s personal opinion of the case before the court. In either case, such evidence is not particularly credible. Generally, the contents of lawyers’ affidavits of this sort can be ignored on motions for summary judgment: Victoria Mendes et al. v. Blaisdale Montessori School, 2014 ONSC 3178 (CanLII) at para. 3, aff’d 2014 ONCA 821 (CanLII).
 It also should be borne in mind that lawyer’s affidavits risk contravening the “lawyer as witness” rules of ethics. Rule 5.2 of the Law Society of Upper Canada’s Rules of Professional Conduct provides:
SECTION 5.2 THE LAWYER AS WITNESS
Submission of Evidence
A lawyer who appears as advocate shall not testify or submit their own affidavit evidence before the tribunal unless
(a) permitted to do so by law, the tribunal, the rules of court or the rules of procedure of the tribunal, or
(b) the matter is purely formal or uncontroverted.
 A lawyer should not express personal opinions or beliefs or assert as a fact anything that is properly subject to legal proof, cross-examination, or challenge. The lawyer should not in effect appear as an unsworn witness or put the lawyer’s own credibility in issue. The lawyer who is a necessary witness should testify and entrust the conduct of the case to another lawyer. There are no restrictions on the advocate’s right to cross-examine another lawyer, however, and the lawyer who does appear as a witness should not expect to receive special treatment because of professional status.
 In addition, among the commentaries to Rule 5.1-1 is the following:
 A lawyer should refrain from expressing the lawyer’s personal opinions on the merits of a client’s case to a court or tribunal.