Ontario Court of Justice

DATE: 2026 03 05

COURT FILE No.: Lanark 998 24 18100416

Parties

BETWEEN:

HIS MAJESTY THE KING

— AND —

MARK MACCHESNEY

Before Justice David S. Rose

Heard on February 2, 2026

Reasons for Judgment released on March 5, 2026

Counsel:

Mr. Corbella, counsel for the Crown

Ms. Zaia, counsel for Mark MacChesney

Reasons for Judgment

Rose J.:

[1] On October 23, 2025, I found Mr. MacChesney guilty of assaulting his ex-wife Malory Seaboyer; on August 1, 2020; on September 13, 2022; and November 14, 2022. I also found him guilty of mischief by damaging a wall in their matrimonial home. Mr. MacChesney was unrepresented at trial and did not call a defence. At sentencing he was represented.

[2] Ms. Seaboyer testified to having a volatile marriage. She said the marriage was fraught and the level of tumult in the home was uncertain on a day to day basis. In August of 2020 she and Mr. MacChesney were fighting and he wanted her to leave the room. He pulled her off the bed with her wrists. He then climbed on top of her and brought his elbow across her neck leaving scratches to her neck.

[3] On September 13 of 2022 Mr. MacChesney threw a pillow at her, which landed outside the bedroom. Ms. Seaboyer went to retrieve it and when she returned to the bedroom the door was locked. She got a key to the door from elsewhere in the house and unlocked it to find Mr. MacChesney standing in the doorway. He refused to let her in. Mr. MacChesney spat on her and grabbed her bottom lip. He grabbed her by the hair and pulled her down to the floor. That is the second assault.

[4] On November 14, 2022 Ms. Seaboyer had returned home from a medical procedure at the local hospital. She lay in her bed to recover. Mr. MacChesney entered the room, kicked the wall. Ms. Seaboyer left the room and when she reached the front door he grabbed her by the shirt and ripped it. He then shoved her backward. She went back to her bedroom to lay down, when Mr. MacChesney entered the room and threw an egg at her hitting the wall. He then cleaned up the mess and shoved it in her face. He told her that he was "putting the garbage where the garbage belongs".

[5] Victim input by Ms. Seaboyer speaks of her time married to Mr. MacChesney. Beyond the specific offences at this trial she spoke of walking on eggshells throughout the marriage to avoid outbursts. She suffered physical, psychological and emotional abuse which eroded her confidence and stripped her of her self-worth. She suffered from a disruption to her eating and sleeping habits. As she said..."the damage is deep and enduring".

[6] The pre-sentence report documents Mr. MacChesney at being 41 years old. He has no criminal record, and a high school education. The PSR documents some of Mr. MacChesney's 20 year service in the Canadian Forces (CF). Notably in 2009 he joined Special Forces and became an active duty member in 2011. He was deployed to Iraq five times, and Afghanistan 3 times between 2011 and 2023. In 2025 he became an infantry instructor and has been on medical limitation work since July 2025. He told the PSR writer that he is no longer capable of serving in the military because of physical and mental health issues. He sustained several injuries during the course of his service, including multiple concussions, a shoulder and neck injury. He self reports to PTSD and anxiety. It would appear that he is having trouble with the divorce process and being unable to see his children.

[7] Mr. MacChesney's father told the PSR writer that he believes his son has PTSD from his military service. Notably, he said that " ...when his son returned from deployment, he noticed he was more distant than usual", and "...his son should have been given more time between deployments to readapt to normal life".

[8] Material provided by Ms Zaia goes into this in some detail. One of his colleagues In CF said "He did not break because he had faced death or physical danger, but because the thought of losing his children was more than he could bear". Another of his colleagues in Special Forces Adam Holmes referred to serving in theater with Mr. MacChesney. He said, with purposeful vagueness, "On another operation we observed enemy combatants attempting to maneuver and engage a friendly force from another nation. Mark quickly assessed the situation and expediently decided how to appropriately deal with the immediate danger presented before us. He utilized every member of our team to quickly determine the best means of interventions....His actions prevented the loss of life or injury to the forces of another nation".

[9] Mr. MacChesney's service record as filed confirms his service. He has received six Military Honours for his service in combat. He holds the rank of Sergeant.

[10] Upon receiving the materials for sentencing I provided an academic article to Mr. Corbella and Ms. Zaia. In Court I invited submissions. The article is "Military-related traumatic brain injury and neurodegeneration" McKee and Robinson Alzheimers Dement 2014 June 10(3 0) S 242- 253. That article is not evidence. It is research based guidance on some of the observed effects of combat on the cognitive function of soldiers by two reputable institutions. I provided that to both counsel, because the study, though a small sample of 5 soldiers, examined soldiers in both Iraq and Afghanistan. It appears that military service by those exposed to weapons and ordinance fire, ie. explosive blast, suffer traumatic brain injury, or TBI, and concussion. Notably, the study observes the behavioural changes which result from exposure to explosive blast by soldiers in combat.

[11] The authors conclude that "it has been increasingly recognized that there is a frequent association of mTBI and PTSD in modern warfare". This may include "...alterations in working memory, planning, multitasking, complex decision making, judgement, empathy, executive function, impulsivity, emotional lability and disinhibition, as well as changes in personality, social behaviour and sleep".

[12] To be sure, the authors conclude that understanding the effects of mTBI from military services is difficult. There are no "..objective biomarkers of the acute injury" in existence. It would appear that the only way of physically confirming the nature of the brain injury is from a post mortem examination. Each of the study participants appears to have died by suicide, violent death or a brain hemorrhage.

[13] In submissions Mr. Corbella argued that there is no evidence of TBI or PTSD on the part of Mr. MacChesney. I disagree. As the collateral sources at sentencing provide, Mr. MacChesney has suffered verifiable concussions from his service. He fell out of a helicopter, suffered a parachuting accident, and fell off a motorcycle in training. His concussions from known accidents in service are documented. In addition, his father's words that he became "more distant" after his tours of duty, and that his deployments were too rapid are to be given real weight. The medical documentation from Capt. Vergie MD in 2018 that he has multiple brain concussions and mTBI mild to moderate are also to be given real weight.

[14] Over and above that, what is left unsaid, but obvious nonetheless, is that Mr. MacChesney's service for CF involved infantryman combat and all that comes with it. He was the tip of the spear in service of the Canadian Government's kinetic foreign policy. It is an inference that he was exposed to explosive blast of one form or another during his service, although there is no mention of that in the evidence. As a member of JTF 2 the full narrative of his time in uniform is not publicly available to a civilian Court such as this. I would not impose a burden on Mr. MacChesney to furnish such detailed information. It is not possible in the context of this case. However, the letter from his colleague Mr. Holmes, a Medal of Valour recipient himself, furnishes this finding.

[15] The material confirming Mr. MacChesney's service is relevant for different purposes. His character, and public service are both mitigating factors on sentence. But I find that they also bear on his moral responsibility. On the evidence and material before me, I find that the effects of Mr. MacChesney's concussions and PTSD from combat in CF lessen his moral responsibility. While I am often asked to consider concussions or PTSD in the context of a sentencing, this is the first time in my judicial career that I have been asked to make that finding in the context of a Canadian combat soldier. In my finding his moral responsibility is lessened.

[16] He took psychotherapy from August of 2023 to September of 2025 with complaints of low mood, energy and sleep. He spent significant time in those sessions dealing with the breakdown of his marriage and issues related to seeing his daughters. Mr. MacChesney's counselling documentation was filed as part of the sentencing. He completed the PAR program on February 25, 2025. More recently he has taken counselling through his army base from June of 2025 up to January of 2026. It therefore appears that he has been in counselling from August of 2023 to today.

[17] Other character letters filed at sentencing confirm Mr. MacChesney to be well thought of by many in the community. His family, colleagues, friend and a neighbour all wrote extremely positive letters in support of him.

[18] The collateral consequences of Mr. MacChesney receiving a conviction were outlined in a letter from a private lawyer who reviewed his file. In the opinion of Mr. Fowler it is a near certainty that Mr. MacChesney will be terminated from the CF with a compulsory release. If he is not Honourably Released he will not be eligible for employment with the Federal Public Administration, and he will be ineligible for Education and Training Benefits which assist veterans in their re-integration into civilian society so that he can gain employment as a civilian. That benefit is considerable. A conviction would "probably" foreclose the possibility that Sgt. MacChesney would be Honourably Released. If he is discharged in this case there is a good chance he will be Honourably Released.

[19] From the material filed at this sentencing I find that the collateral consequences to a conviction are significant. The collateral consequences to Mr. MacChesney are not simply monetary. Having served in the CF for nearly 20 years in a high risk role a conviction would seriously risk him being released into civilian life with none of the necessary support to make that transition. His service to Canada would amount to very little going forward. Beyond that, releasing a combat soldier to civilian life without support for that transition strikes me, at best, as contrary to the public interest, and I so find.

[20] A person found guilty of an offence may be discharged according to the test under s. 730 of the Criminal Code. The test is twofold: is it in the best interest of the accused, and will a discharge not be contrary to the public interest. In this case the real question is the latter, namely would granting a discharge to Mr. MacChesney be contrary to the public interest? The first part of the test is easily answered in the affirmative.

[21] For these reasons I find that the aggravating factors in this case are:

• The level of humiliation in the encounters. In this case Mr. MacChesney called Ms. Seaboyer a "cunt", and wiped egg into her face;
• This is a case of intimate partner violence. Ms. Seaboyer is entitled to live in her house free of intimidation and violence.
• Ms. Seaboyer suffered a scratch on her neck from the August 2020 incident. She did not need medical attention but it is a physical injury nonetheless to Ms. Seaboyer;
• The Victim Input is vivid. Ms. Seaboyer said that, "There were days I could not eat, nights I could not sleep, and many moments I genuinely feared for my life. Even now I carry the weight of what I endured"

[22] There are numerous mitigating factors too:

• The last of these incidents happened nearly 3.5 years ago. He has separated from Ms. Seaboyer and has no contact with his children. I am told that the divorce and custody issues are before the Court in New Brunswick;
• His character letters from his colleagues, family and neighbours are quite positive;
• Mr. MacChesney has taken counselling from well before this trial commenced. He has completed the PAR program already. He continues to be under counselling within mental health services at his base;
• His service to the country as an active member of CF has gone on for 19 years. I have described his service in detail above and there is no need to dwell on it further;
• His service related injuries have resulted in three concussions that are documented. He was diagnosed with TBI in 2018. Although not necessary to make this finding I also would not ignore the very real possibility that he has suffered explosive blast injuries from his service. The specific nature of his service was described in the materials before me and the impact this had on his emotional health was described by his father. This mitigates his moral responsibility for the emotional instability in evidence in the events in his home in 2020 and 2022.
• I find that there is a link between his service related concussions and the mental health deterioration documented by his father, and his counsellor from 2023 and 2024 documenting his low mood. As his father put it, the deployments were too rapid and he became more distant. That is telling, when combined with the balance of evidence filed at sentencing. It is not lost on this Court that combat soldiers have every incentive to minimize their mental health problems for fear of getting dropped from their unit. In my finding it is time to move past the point where those in high risk occupations must prove the entirety of their mental health deterioration during their career – ones which might potentially end their career. That is a paradox and one which minimizes the nature of high risk roles such as special forces soldiers.
• The collateral consequences of a conviction are significant. The impact of collateral consequences is distinct from reduced moral blameworthiness. Collateral consequences permits adjustments in the sentence so long as the imposed sentence continues to reflect the gravity of the offence and the moral responsibility of the offender, see R. v. Morgan, 2020 ONCA 279.

[23] In this case the Crown asks for a 4 month conditional sentence. Given the many significant mitigating circumstances I find that a custodial sentence, even one on the community, is unnecessary. While Ms. Seaboyer suffered from psychological injury a bruised lip, and a scratch on her neck, the level of physical injury and passage of time since the assaults combine to minimize the need for a custodial sentence to serve the denunciatory and deterrent requirements of this sentence.

[24] The Crown provided appellate jurisprudence which stands for the proposition that "the range of sentences handed down in cases of domestic violence demonstrate a very clear trend, according to which the objectives of denunciation and deterrence must be given significant, if not predominant weight" see R. v. Mputu (unreported 2024) Dunphy J. sitting on Summary Conviction Appeal, R. v. Ibrahim, 2011 ONCA 611 as quoted in R. v. P.B., 2026 ONCJ 16, R. v. Boucher, 2004 CanLII 17719 (ON CA), [2004] O.J. No. 2689, R. v. Tarren, 2017 ONSC 5618. I have considered this guidance and I find that in cases of intimate partner violence denunciation and deterrence are the predominant factors on sentencing. Because a discharge is a lawful sentence under s. 730 a discharge will only be an appropriate sentence in exceptional cases, particularly after a trial. After considering the various factors for some time, I have come to the conclusion that, in the unusual factors of this case, Mr. MacChesney should be discharged.

[25] Accordingly, in this case Mr. MacChesney will be discharged upon completing 18 months of probation. The terms will be:

i) No contact with Malory Seaboyer except:

a) Through legal counsel;

b) Pursuant to a Family Court Order in any jurisdiction in Canada;

c) For purposes of attending Family Court proceedings, either with or without the presence of counsel;

d) For purposes of coordinating insurance benefits;

e) Pursuant to a separation agreement agreed to by Ms. Seaboyer;

f) Through presence of a third party approved by Ms. Seaboyer.

ii) Not to possess weapons except for purposes of employment and with the approval of Canadian Armed Forces.

iii) Report to a probation officer within 2 business days by telephone and thereafter as directed by probation staff;

iv) Take counselling as directed by Probation staff, and sign releases as required to monitor enrollment, attendance and completion of counselling;

[26] The Assault charges are secondary designated offences under the National DNA Identification Act and it is in the best interest of the administration of justice that Mr. MacChesney supply a sample of his DNA to the National databank.

[27] Both Mr. Corbella's and Ms. Zaia's submissions were candid and helpful in this difficult sentencing and I am grateful for their assistance.

Released: March 5, 2026

Signed: Justice Rose