Wielding the A300 Standards as a Shield

When I first sat down to breeze through the American National Standards Institute (ANSI) Tree, Shrub, and Other Woody Plant Management – Standard Practices years ago, my initial reaction was how self-evident the requirements were. Before I opened these documents, I was expecting to learn new sage advice about professional practice. But now I know I was approaching the standards all wrong.

What I did not understand at the time was, as consensus documents, the “standards” are a documentation of what industry stakeholders can agree upon within the context of the ANSI approval process. The power behind these standards is not from imparting knowledge of yore, but rather, it is an articulation of what is generally acceptable and unacceptable by the industry. When wielded correctly, the standards can be powerful defensive legal weaponry.

After I finished my perusal of the standards years ago, I set them down on a shelf and put them out of mind. Since then, I’ve encountered the standards briefly in abstracts or job specifications, but I had never studied them carefully until my most recent read-through, when I realized the power contained in their text.

In this article, I highlight a few important sections in Parts 1 and 9 of the standards and how they can be used as defensive tools for practicing arborists.

Applicability to individuals

“Duty of care” is the legal obligation to take reasonable action when performing tasks that can harm others. “Standard of care” is the degree of care that a person must exercise in fulfilling a duty of care. The A300 standards can be used as evidence to help a court of law determine who owes a duty of care and what standard of care each individual will be held to.

Section 1.3 articulates the individuals to whom the standards apply:

“ANSI A300 standards shall apply to any person or entity engaged in the management of trees, shrubs, palms, or other woody plants, including federal, state or local agencies, utilities, arborists, consultants, arboricultural or landscape firms, and managers or owners of property.”

The breadth of this statement makes the A300 standards document powerful, because it applies to everyone listed, whether you are an arborist, consultant or landscape designer. If one of these listed people fails to perform any of the following sections containing the word “shall,” then that person is in violation of the standards. Because of Section 1.3, these standards may be used as evidence that even a non-arborist has breached their duty of care.

How many times have you seen the A300 standards incorporated by reference in the specifications of a contract? Whether they’re aware of it or not, the agencies or tree owners handing you those specifications are binding themselves to the standards as well! Section 1.3 appears on its face to apply universally, without the prerequisite of an individual affirmatively accepting it, but there is a much stronger argument that the standards should be enforced as a duty if a manager’s signature is on a contract that references them. If the standards are being used as evidence against a defendant, that defendant cannot dodge responsibility by saying “I’m not an arborist” if that individual meets the description of another party listed, nor can that individual claim the defense of not having read the standards.

Furthermore, each and every section of the standards applies, even when not referenced directly. Section 3 of Part 1 is a list of “Normative References.” These are documents incorporated by reference; simply by being listed as a whole, all of the individual standards are included. That means if a pruning crew acknowledges it is held to the pruning standards of Part 1, it must also be held to the standards listed in Part 9, Risk Assessment.

Defensive application: The shield

Tree-risk assessors and tree care companies alike can be expected to perform an inspection of the trees within their scope of work. Depending on the scope of the assessment, some tree defects may be observed, and some may not. Referencing Part 9 of the A300 standards is an effective way of articulating the limits of the Standard of Care that assessors will be held to. These are the rules that limit the scope of a risk assessment to the trees, targets and level specified in the scope of work.

Job specifications

Section 93.5 states, “Tree risk assessors shall not be required to assess trees other than those included in the specifications.” This protects assessors from being held to inspect trees not included in scope. Suppose a tree not included in the scope of work fails and causes damage. The tree assessor will have a strong defense if he or she references 93.5 and can show that the scope of work does not include the failed tree. Per Section 1.3 (discussed above), this section binds both the assessor and the manager, thereby limiting the duty owed by the risk assessor.

Similarly, Section 93.6 reads, “Tree risk assessors shall not be required to perform a higher level of assessment than specified.” This protects assessors from being expected to use a tool or test that is not listed in the scope of work. Per 94.5.2, any tools or techniques not included in a Level 1-2 assessment would be a Level 3 assessment. If a Level 3 assessment is not explicitly listed in the scope of work, then the assessor has a strong defense that he or she should not have been required to have used additional tools or techniques to detect defects when conducting tree-risk assessment.

Suppose a tree is hollow, but there are no signs of internal decay after an arborist performs a Level 2 Basic, all-visual inspection as specified in a contract. Even if decay could have been detected by performing a drilling test or pull test, the arborist would not be held responsible for such advanced detection methods. If the tree failed, the arborist would have a strong defense to a claim of negligence by showing a copy of his or her scope of work (“Level 2 Basic assessment”) and then pointing to 93.6. According to the A300 standards, the assessor would have a good argument that he or she acted as a “reasonably prudent person.” Failing to detect the decay may not have been a breach of the duty of care.

There are a number of tools that may be used as part of a Level 2 Basic inspection, including binoculars, mallet, probe, compass, camera and measuring tools. These tools do not elevate a Level 2 Basic inspection to a Level 3 Advanced assessment. However, they are optional; an arborist may choose to use them or not. If the inspection specifications are clear that an inspection will be all visual or will only use one or two of those tools, the arborist has a good defense that he or she acted as a “reasonably prudent person,” if the specifications are followed.

Level of inspection

Another critical defensive maneuver relates to a Level 1 Limited visual assessment. Often arborists are asked to perform quick look-and-see inspections. In the interest of speed, only obvious defects are observed and reported. But which targets and tree parts should be considered?

Section 94.3.1 answers this question: “The tree(s), targets, and unique conditions of concern (if any) to be considered in Level 1 assessments shall be specified.” That means three things:

  • If a tree is not specified, it is not included;
  • If a target is not specified, it is not included; and
  • If the conditions of concern are not specified, they are not included.

This is a powerful defense for an arborist performing a Level 1 Limited visual inspection! 94.3.1 protects arborists from clients later claiming a loss resulting from a target, tree or tree part not explicitly spelled out in the scope of work. If the client were to claim that the arborist ought to be held to have inspected for an unlisted attribute, then the client would have been in violation of this standard.

Citing 94.3.1 as a defense can turn the client’s claim into a contradiction. If a tree, tree part or target is not listed in the scope of work, then one of two things would have to be true:

  1. The client failed to include the unlisted attributes in the scope of work, and thus the assessor should not be held to inspecting for them; or
  2. The client violated the A300 standards.

There’s a lesson here for tree assessors and service providers. In your scope of work, make sure to specify which tree parts you will be evaluating. According to 94.3.1, if an assessor states he or she will look for “branch defects” in their scope of work and then an inspected tree fails at the root crown, they would have a good defense for why they should not be held responsible for looking for root-crown defects.

The exception language from 94.3.1 only applies to Level 1 Limited visual assessments. That means it is advantageous for tree assessors and service providers to have some language in their contracts stating their inspections are Level 1 Limited visual. How can this be done so categorically? If you look at a tree from the ground, aren’t you performing a Level 2 Basic assessment? Not necessarily. 94.3.2 requires that the perspective of the assessment be specified. It provides examples of different perspectives, among them being “one-sided, ground-based.”

So, if you specify in your contract or tree-service bid forms that you are only inspecting the trees with a Level 1 Limited visual assessment from a one-sided, ground-based perspective, then you would have an argument that your inspection should not be held to the same standard as even a Level 2 Basic assessment. But don’t forget, you also must include a description of the trees, tree parts and targets considered, or else you will be in violation of 94.3.1!


In the context of conflict resolution, the ANSI standards can be powerful tools to bring into battle. They articulate who will be bound by their guidelines and provide a shield with which practitioners can defend themselves from claims of negligence.

Be aware of the interaction between the standards and your contracts and scope-of-work documents. Be aware of the interrelation of all the standards. And, above all, be aware of what knowledge and level of competence you will be held to if things go wrong.

I hope that after reading this article, you’ll be inspired to dust off those standards and give them a much more thorough reading.

James Komen operates Class One Arboriculture consulting services in Glendora, California. He teaches classes on the topics of risk assessment and tree appraisal around the U.S. and Canada. This article was based on his presentation, “Wielding the A300 Standards Every Day,” at TCI EXPO ’21 last November in Indianapolis, Indiana. To listen to an audio recording of that presentation, go to tcimag.tcia.org and, under the Resources tab, click audios. Or, under the Current Issues tab, click View Digimag, then go to this page and click here.

Portions of this piece previously appeared in a variation of this article published in the February 2020 issue of Arborist News.

Click here to learn more about the ANSI A300 standards!

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