CONTRACTORS: Answers to 8 FAQs about Contractors and the OHS Law


It’s common for companies to engage outside contractors to do certain work for them, such as cleaning their offices or doing electrical work at a construction project. Just like the company that hires them, contractors are obligated to comply with the OHS laws and are subject to safety violations if they fail to do so. But the hiring company could also be liable for a contractor’s safety violations. So it’s important to understand the relationship between employers and contractors, and how the OHS laws address the issue of contractors and liability for their OHS offences. To help you understand this complex topic, here are answers to eight frequently asked questions (FAQs) about contractors and the OHS laws.


Q Do the OHS Laws Define Contractor?

A It depends on the jurisdictions, but in many cases, the answer is yes. Several jurisdictions specifically define the term “contractor” or related terms in their OHS laws. For example, Sec. 1(e) of Prince Edward Island’s OHS Act defines “contractor” as “a person who contracts for work to be performed at the workplace of the person contracting to have the work performed, but does not include a constructor.” Related terms include:

  • Prime or principal contractor, which is usually defined as the person primarily responsible for the carrying out of a project and includes the person who owns the thing in respect of which the project is being carried out; and
  • Constructor, which is typically defined as a person who contracts to do work on a construction project for an owner or who undertakes work on a construction project as an owner.

Note that these related terms generally apply only to construction-related projects or sites, which include the construction, demolition, renovation, etc. of buildings and other structures as well as related work on the land, such as excavations and trenching. This approach makes sense because construction sites are both very hazardous and usually involve work being done by a variety of different companies. Thus, several jurisdictions have specific requirements for contractors at construction sites to better ensure the safety of all workers at such sites. (However, some jurisdictions, including AB, BC and SK, allow or require prime contractors at any worksite where there are multiple employers.)

Q Do Contractors Have Specific OHS Duties?

A The jurisdictions that define contractor—and prime/principal contractor and constructor—usually include specific duties for those entities in their OHS laws. For example, Sec. 14 of Nova Scotia’s OHS Act requires every contractor to take every precaution that’s reasonable in the circumstances to ensure:

  • The health and safety of persons at or near a workplace;
  • That the activities of the employers and self-employed persons at the workplace are coordinated;
  • Communication between the employers and self-employed persons at the workplace of information necessary to the health and safety of persons at the workplace;
  • That the measures and procedures required by the OHS act and regulations are carried out at the workplace; and
  • That every employee, self-employed person and employer performing work at the workplace complies with the OHS act and regulations.

And Sec. 23(1) of Ontario’s OHS Act says that a constructor must ensure, on a project undertaken by the constructor that:

  • The measures and procedures required by the OHS act and regulations are carried out on the project;
  • Every employer and every worker performing work on the project complies with the OHS act and regulations; and
  • The health and safety of workers on the project is protected.

The above duties are very similar to the general duties of an employer. In fact, those jurisdictions that don’t specifically include duties for contractors in their OHS laws may, in fact, include “contractor” in their definition of “employer” and thus impose an employer’s duties on contractors indirectly.

Q Can You Delegate OHS Duties to a Contractor?

A Although many OHS duties can’t be delegated, you may be able to delegate some duties to a contractor, particularly for a construction project. For example, in Alberta, a “prime contractor” is required at worksites with multiple employers. Unless other arrangements are made, the owner of the worksite is the prime contractor. But the owner can sign a written agreement transferring that title—and its related responsibilities—to another individual or company that’s capable of fulfilling the prime contractor duties. However, as a bulletin on prime contractors explains, “even with the appointment of a prime contractor, each employer, worker, contractor, and supplier retains responsibility for ensuring the health and safety of workers.”

Bottom line: Under no circumstances may an employer delegate all of its responsibilities under the OHS laws to a contractor, prime contractor or someone else. So don’t think using contractors will get you completely off the hook for compliance with the OHS laws. Employers are ultimately responsible for the health and safety of their workers.

Q When Can You Be Liable for a Contractor’s Safety Violations?

A As noted above, employers, contractors, prime/principal contractors and constructors have a general duty to comply with the OHS laws. Thus, they can all be liable for a safety offence if they violate those laws. But employers that use contractors are also exposed to at least some degree of liability for safety offences committed by those contractors—even if they designate the contractor as a prime/principal contractor or constructor. (Contractors may also be liable for any safety violations committed by their subcontractors.) In addition, if a contractor’s worker is injured or killed on the job, the employer that hired the contractor could face liability for that incident.

Example: A mushroom farm was undergoing extensive construction that included new concrete pads. A worker was driving a front-end loader to pick up compost from one end of the new pad and drop it into a hopper at the other end. A worker employed by a sub-contractor was crossing the concrete pad when he struck by the loader while it was going in reverse. He died at the scene. The farm pleaded guilty to failing, as an employer, to ensure that workers didn’t walk on the concrete pad while a loader was being operated and was fined $140,000 [Monaghan Mushrooms Ltd., Ontario Govt. News Release, April 10, 2014].

Q How Can You Protect Yourself When Hiring Contractors?

A The first step in protecting yourself from liability for contractors’ acts or omissions is to take reasonable care when hiring them to ensure they’re qualified to do the work, and do it safely and in compliance with the OHS laws. Some reasonable steps you can take to screen prospective contractors include:

Hiring contractors with valid Certificates of Recognition. One way to screen contractors is by hiring only contractors that have a valid “Certificate of Recognition,” a credential issued by the workers’ comp boards of many jurisdictions, such as AB, BC, ON and SK. Having a valid certificate indicates that the contractor has met stringent health and safety requirements.

Auditing prospective contractors. You can also audit a contractor’s OHS program, either yourself or using an outside agency or registry. For an audit to be effective, you should screen contractors with an eye on your particular project and the job for which you’re considering the contractors. For example, if the contractor would be doing electrical work on your project, then you need to ensure that it has written safe work procedures in place to protect workers from electrocution, trains workers on those procedures and disciplines workers who violate procedure.

In addition, there are certain criteria you should always consider when evaluating contractors:

  • Their OHS system, including whether they have written safe work policies, a safety manual, an orientation for new workers, comprehensive training and testing of workers to ensure they understand their training;
  • Their supervisors’ qualifications and training;
  • Their workers’ comp rating as compared to other companies in their industry;
  • Their safety record, including orders, charges, violations and convictions; and
  • Results of recent safety audits conducted on or by them.

Screening workers and supervisors, too. Yes, you should screen the contractor’s OHS program. But it’s also important to screen the workers and supervisors who’ll actually be doing the work you hire the contractor to do. A company may have a great overall OHS program and safety record but those qualifications won’t do you any good if the particular crew it sends to your workplace is inexperienced or led by a careless supervisor. So if possible, try to get information on the crew and supervisors who’ll be assigned to your job, including their experience, training and safety records.

Insider Says: For more on screening contractors, see How to Do Prequalification Safety Audits. And use this Contractor Document Checklist to ensure you get all the documents you need to effectively evaluate a prospective contractor.

Q What Should You Include in an Agreement with a Contractor?

A Once you’ve selected a contractor that passes your screening process, the next reasonable step you should take is to include certain requirements and protections in the written agreement you sign with it. For example, your agreement should require the contractor to:

Comply with specific safety procedures. A basic requirements is that the contractor must comply with the OHS laws and industry standards. But it’s wise to go further and state whether the work to be done must comply with your or the contractor’s safety procedures and OHS program.

Get your consent before hiring subcontractors. A contractor may need to hire subcontractors to do certain aspects of the job for which it’s been hired. But if you’re going to give the contractor the power to hire subcontractors, require it to get your consent first and retain the right to refuse to allow the contractor to hire a subcontractor that you believe is unqualified or unsafe.

Indemnify your company. The contractor should “indemnify” your company—that is, it should agree to pay or reimburse the company for any and all costs related to any safety violations it causes, including fines, lawyers’ fees, experts’ fees, investigatory costs and any other related expenses.

Cooperate in the event of an incident. Require the contractor to cooperate with you regarding any safety incident that occurs involving the contractor and its workers, including requiring it to report such incidents to you. You’ll likely need such cooperation in your investigation of the incident or to respond to any investigation by your OHS regulator into the incident. For example, you may need training records for the workers involved or access to workers who witnessed the incident.

INCIDENT REPORTING FORM: At, you can download and adapt a form that you can require contractors to use to report any incidents to you.

Q Should You Monitor and Supervise Contractors?

A Yes! You can’t assume that a contractor will comply with the OHS laws and its safety obligations just because they’re required to do so in your written agreement. It’s critical that you monitor and adequately supervise the contractor while it’s working for you to ensure that it does what it promised to do. If you don’t supervise a contractor and it violates an OHS law, your company could be held responsible for that violation.

Example: At a BC construction site, a painting contractor and one of his workers were injured in a fall from a ladder on a roof. Neither was wearing fall protection. The prime contractor for the site was issued an administrative penalty for OHS violations and appealed, arguing that the painting contractor was at fault and it had exercised due diligence to ensure the contractor complied with the OHS laws.

The Tribunal disagreed. The issue was whether the prime contractor had in place a generally effective safety system as well as specific systems relevant to the particular site and contractor to ensure it complied with its safety obligations under the OHS laws. A prime contractor can’t merely assume that contractors will work safely; it must proactively ensure such safe work takes place. Here, the prime contractor had a general oversight system, but failed to effectively oversee this specific worksite and the painting contractor. For example, although the prime contractor gave the painting contractor an orientation and explained what his duties were, it didn’t otherwise supervise him or his workers. And it knew that the painting contractor was attending the worksite at irregular and unscheduled hours, without contacting the site superintendent and thus without direct supervision.

The Tribunal explained that because contractors aren’t always motivated to comply with their safety obligations, multi-employer worksites place an added supervisory duty on the prime contractor, who’s in the best position to control and ensure safety on such worksites. So although the painting contractor was obviously at fault, the prime contractor’s failure to adequately supervise him reflects, in turn, a breach of its own safety obligations, concluded the Tribunal [WCAT-2013-03358 (Re), [2013] CanLII 80101 (BC WCAT), Nov. 29, 2013].

To ensure that you adequately supervise contractors:

Tailor the level of supervision to the level of hazard. All work doesn’t require the same level of supervision. That is, the greater the hazard, the greater the need for supervision of contractors. For example, particularly hazardous work, such as jobs involving confined spaces or work being done at heights, requires more direct supervision, such as having someone from your company physically monitor the contractor in the field. But for less hazardous work, you can usually rely on indirect supervision, such as requiring daily copies of all risk assessments conducted by the contractor.

Look for safety violations and infractions. When supervising a contractor’s work, you shouldn’t merely ensure that the workers are doing the job they were hired to do. It’s important that you also identify any violations of the OHS laws and of your company’s or the contractor’s safety rules and procedures. The existence of such infractions may, in fact, signal that this contractor needs more direct and frequent supervision.

Q What Should You Do if a Contractor Isn’t Compliant?

A As noted above, while supervising contractors, you may uncover violations of the OHS laws or of the contractor’s safety duties under your agreement with it, such as workers not wearing PPE or following safe work procedures. If you’ve identified any such violations, you must take appropriate steps in response. For example, if your site superintendent sees a contractor’s workers not wearing hardhats on a construction site, he should immediately speak to a supervisor for the contractor, advise him of the infraction and require those workers to use proper PPE. The appropriate action will vary depending on the nature of the violation, ranging from a verbal warning to termination of the agreement.

Think twice before directly confronting a prime/principal contractor’s or constructor’s worker who’s noncompliant because doing so can have unexpected consequences. For example, by asserting your authority or control over the worker and the work, you may inadvertently undercut the limited protection you get from the designation of the contractor as prime/principal contractor or constructor.

Example: The NWT Department of Transportation (DOT) owns the ferry, landings and incidental shore equipment at a ferry crossing but contracts out the ferry’s operation to a company. After driftwood and debris got tangled in the ferry cable, three ferry company workers began loosening nuts securing the cable, which suddenly started whipping back and forth. It struck and injured two workers. At the time, a DOT marine engineer was supervising the workers. The DOT and ferry company pleaded guilty to OHS violations.

In fining the DOT $75,000, the court commented on the relationship between the DOT and the ferry company as it related to the DOT’s blameworthiness. Under the contract, the ferry company was required to comply with all laws, perform its services in a safe manner and employ a superintendent to direct and supervise these services. But on the day of the incident, a DOT employee—the engineer—was supervising the ferry company workers, removing the “protective curtain” between the DOT and the company, said the court. And when the DOT began instructing and supervising the workers, it also assumed the duty of ensuring that the work was performed safely. So although the contract put responsibility for safety in the ferry company’s hands, the DOT could no longer say it was protected by the contract, concluded the court [R. v. GNWT (DOT) and Grizzly Marine Services Ltd., [2014] NWTTC 17 (CanLII), June 27, 2014].

Lesson: If you take actions that contradict the terms of an agreement with a contractor, such as directing how a contractor’s worker does a job or reprimanding him for a safety infraction, you may lose any protections from liability in that agreement. So instead of, say, telling a contractor’s worker to use appropriate fall protection, you should tell the contractor about the issue and instruct it to compel the worker to wear proper PPE.


For many companies, the use of contractors is unavoidable. Although managing contractors and avoiding liability for their safety violations is complex, it can be done. Just take steps to ensure that your company hires contractors that are qualified to perform the work and have good safety compliance track records, and then supervise them to ensure that they fulfill their safety duties. For more information, tools and other resources on dealing with contractors, go to the OHS Insider’s Contractor Compliance Centre.