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Pt. Reyes Light

Trees: whatís your liability?
Point Reyes Light, January 18, 2007

By Thomas Yeatts

There are no laws strictly defining the number of times a tree must be inspected or pruned. Negligence is often defined by determining first what a "reasonable" person "of ordinary prudence" would do to prevent injury, according to Barri Bonapart, an attorney specializing in tree law.


The concept of notice is important to determining liability. "If someone was on notice that something was wrong with a tree and they chose to ignore it, and then something happened, thatís clearly an act of negligence," Bonapart said.

"But negligence is not only just knowing," she said. "Negligence is whether you knew or should have known." One cannot turn a blind eye and then, when an accident happens, claim ignorance. Individuals must be careful that their trees do not exhibit "red flags" like overly exposed roots, a split trunk, or cut roots.

Active and passive negligence

In determining the degree of negligence, the law distinguishes between active and passive negligence. An example of active negligence is performing construction work that severs root arteries, and failing to address the problem. An example of passive negligence is failing to follow up on a visual inspection with a more in-depth and detailed hazard assessment, like a root crown analysis or resistograph test.

In 1995, a eucalyptus tree fell across a highway and badly injured a correctional facilities officer on his way to work. The eucalyptus was part of a group of trees, partly owned by Caltrans, and partly owned by a private rancher. On inspection it was discovered that not only was this tree not the first in the group to fall, but the roots had been cut and some of the trunks were rotted. Both Caltrans and the rancher were found liable on the basis of both active and passive negligence.

In another case, a fir tree fell during a winter storm in Dec. 2002 onto a Calistoga residentís house from an adjacent property, destroying the house and nearly killing those inside. According to the case records, the residents were "in bed asleep when their home was sliced in two. They narrowly escaped death."

The residents sought Bonapartís legal assistance, alleging that the tree owner was negligent for not having detected the tree was a potential hazard. The neighbor contended that the tree appeared healthy and that its failure was an "act of God" that could not have been predicted or prevented.

This case involved conflicting arborist reports, explained Bonapart. "Our arborist conducted a thorough analysis and inspection and found things the other arborist missed in his earlier investigation." The case was settled in favor of her client.

Act of God

When a tree falls, it is common for property owners and tree caretakers to claim that the accident was unforeseeable, determining it an "act of God", according to Sevier, a certified arborist and tree accident expert based in San Diego, who says the term is "a confusion, a myth, and a rubber stamp Ė a part of insurance underwriting vocabulary."

Sevier has been an expert witness in tree accident reconstruction in close to 200 cases since 1979 in California, Texas, Alabama, Florida, San Juan and elsewhere

"Once a tree has given us a message in the way of limb break events, itís hard to continue to call it an act of God," said Sevier. "An oak may be giving us a warning if its trunk leans, or if its roots are exposed or are being undermined by running water."

"God created the tree, but God also created responsibility," said Sevier. "Trees talk to us. They give us messages. More than half the cases that were initially called an act of God, once thoroughly investigated, were found not to be," he said. Sevier recalls one case in which a Eucalyptus limb fell on a 4-year-old at the San Diego Zoo in the mid 80s, killing the child, and the incident was labeled an act of God. Upon inspection it was determined that there had been a prior limb failure that would have indicated structural vulnerability.

Arborists: certified and consulting

A prudent first step in tree maintenance is to have a qualified arborist survey a property. In the business of tree inspection and maintenance a distinction is made between a certified arborist and a registered consulting arborist. "Sometimes an arborist can be both a certified arborist and a consulting arborist, but they donít necessarily mean the same thing," said Bonapart.

"íCertified arboristí sounds official but itís not. Any guy with a pickup truck and a chainsaw can be a certified arborist if they take the exam." said Bonapart. To be "certified" the applicant must pass an exam, administered by the International Society of Arboriculture throughout the year. Bonapart says a certified arborist, if he has enough experience, could make accurate hazard assessments, but the designation "certified" alone does not qualify one to make judgments about the stability of a treeís structure.

A consulting arborist, on the other hand, has taken courses and passed rigorous exams, in addition to having experience performing hazard assessments and valuations, and may belong to an official organization called the American Society of Consulting Arborists.

There are over 2,000 certified arborists in California, and over 15,000 worldwide, with the heaviest concentration in the United States. There are 45 registered consulting arborists in California as of 2006. There are many arborists in West Marin who may be qualified to provide hazard assessments. If you are worried about liability, locate a qualified consulting arborist in your area by visiting the website of the American Society of Consulting Arborists at

Reprinted with permission from Pt. Reyes Light. © 2007. Tomales Bay Publishing company.

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