Two women once appeared for trial on on of my traffic court dates. Both were disputing a ticket for failing to wear a seat belt under section 220(4) of the Motor Vehicle Act. They each testified that they were wearing their seat belt, but had placed the shoulder belt under their arms.
This is a common occurrence for women and is more rare for men in my experience. My understanding of the situation is that women tend to do this as they are shorter and the position of the shoulder belt cannot be adjusted. It's uncomfortable for them.
Both women were not successful with their dispute as the law requires that the seat belt be worn "in a properly adjusted and securely fastened manner."
Yes, the ticket said "fail to wear seat belt" instead of "failing to wear seat belt properly." This wording is dictated by law and the officer issuing the ticket has no alternative but to write that in the blank if they want the ticket to be valid. Both circumstances are covered by the ticket, but people get the wrong idea when they feel that they had at least part of the belt on properly and they read these words on the form.
To return to the "properly adjusted and securely fastened manner." Please, take out the owner's manual for your vehicle and read the section on seat belts and airbags. It will specifically warn you not to wear the shoulder belt under your arm along with other common mistakes like wearing them while twisted, too loose, damaged or connected to the wrong buckle.
The belt must be worn snugly over the pelvis and collarbone, not the neck. To be fully protected, you must also be seated upright with your back against the seat. Don't recline or you could "submarine" under the belt during a crash.
It is critical to wear the seat belt properly when your vehicle has an airbag as it holds you in the proper place for the bag to do it's job as well as restraining you during a crash. Being out of position during deployment invites injury from the airbag!
Don't be tempted to buy aftermarket gizmos to help you position your shoulderbelt. They are commonly available and some even imply that they meet safety standards. One standard that I could track down dealt with flammability and did not inspire my confidence in their truthfulness.
The only positioning device that I might have some confidence in is a belt positioning booster seat. Booster seats are not just for children!
If you do need help, see your vehicle's local dealer or an occupational therapist.
What the owner's manual will not tell you is what happens when you wear the shoulder belt under your arm and are involved in a collision. Torn aorta, lacerated liver, ruptured spleen, broken ribs, and this is from the shoulder belt! The large bones of the shoulder will withstand the collision forces much better than the weaker ribs and these internal injuries are much less likely to occur.
Without the shoulder belt to hold your upper body back properly, you will likely to contact the steering wheel or dashboard with your face. That's not a pretty picture, is it?