Me Sébastien Gagnon
Partner & Lawyer
Graduating from Université Laval in 2000 and admitted to the Québec Bar that same year, Me Sébastien Gagnon is a seasoned lawyer with over 20 years of experience in criminal, penal, and administrative law. He began his career in 2001 as a Crown prosecutor in Gatineau, where he gained notable expertise in impaired driving cases, sexual assaults, theft, and fraud. In parallel, he also specialized in handling penal offense tickets, further strengthening his versatility.
In 2006, after a successful career as a Crown prosecutor, Me Gagnon chose to switch to the defense side by joining the firm Leblanc Donaldson, where he took charge of the criminal, penal, and administrative division. This transition allowed him to leverage his experience from the other side of the courtroom, dedicating himself fully to protecting his clients’ rights.
Building on this foundation, Me Gagnon co-founded CSG Avocats in 2015 alongside Me Paul Charlebois and Me Michel Swanston, today the largest criminal law firm in the Outaouais region. His reputation is built on transparency, objectivity, and a strong commitment to providing informed advice while fiercely defending his clients’ interests.
Areas of Expertise
Me Gagnon has deep expertise in various areas of criminal law, including impaired driving, sexual assaults, dangerous driving, assault, theft, and fraud. He also excels in defending penal offense cases, whether under the Highway Safety Code, the Québec Construction Code (CCQ), the Régie du bâtiment du Québec (RBQ), or the Autorité des marchés financiers (AMF).
His skill set also extends to representation before administrative bodies such as the Québec Transport Commission and the Régie des alcools, des courses et des jeux. Additionally, he rigorously defends professionals facing disciplinary proceedings from their professional orders, cementing his reputation as a staunch defender of individual rights.
Involvements:
- Association of Defense Lawyers of Québec
- Association of Defense Lawyers of the Outaouais
- Association of Provincial Defense Lawyers
- Barreau de l’Outaouais
- Professor at the École du Barreau in criminal and penal law
- Professor at La Cité Collégiale in criminal and penal law
- Mentor for criminal law at the Québec Bar
- Trainer at the AJBO (Association du Jeune Barreau de l’Outaouais) in criminal and penal law
Distinctions
Recent successes
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Perjury and acquittal
In a case where the client was charged with perjury, the defense conducted two intense cross-examinations of the prosecution’s witnesses, highlighting significant contradictions in their statements. Following these cross-examinations, a motion for lack of evidence was filed and vigorously argued by Me Gagnon. The judge was convinced that the prosecution’s evidence was insufficient to justify a conviction, and the client was acquitted, thus avoiding a criminal conviction. -
Assault on a child and acquittal
In a case where the client was accused of assaulting a child, the defense conducted rigorous cross-examinations of the prosecution’s witnesses. These examinations exposed contradictions, inconsistencies, and implausibilities in the testimonies. By demonstrating these weaknesses in the evidence, Me Gagnon convinced the judge that there was reasonable doubt about the client’s guilt, leading to an acquittal and avoiding a criminal conviction. -
Impaired driving and charges withdrawn
In a case where the client was charged with impaired driving, Me Gagnon raised the issue of unreasonable delay during the arrest and the vehicle’s towing. By arguing the client’s constitutional rights, particularly under the Charter, he showed that these delays compromised the validity of the procedure. As a result, the charges were withdrawn, allowing the client to avoid a criminal conviction and its consequences. -
Sexual assault and acquittal
In a case involving sexual assault charges, Me Gagnon filed a motion for unreasonable delay, arguing that his client’s rights had been violated due to delays in the judicial process. After the defense presented this motion and advanced constitutional arguments, the court pronounced an acquittal. The client received a peace bond but avoided a criminal conviction while agreeing to certain conditions. -
Sexual assault and charges withdrawn
In another sexual assault case, the charges were withdrawn at the start of the trial. Through rigorous pre-trial questioning, the defense highlighted numerous contradictions in the prosecution’s testimonies and evidence. Thanks to this demonstration of weaknesses in the case, the Crown prosecutor decided to withdraw the charges, sparing the client from trial and criminal conviction.