Re: trees

Yes. It is a form of trespass. If the roots or falling limbs also unreasonably interfere with the neighbor's use and enjoyment of her property, such as endangering her children (falling limbs) or bcckling her driveway (roots), she may also have a case for "private nuisance." Further, if anyone is hurt, you could perhaps be sued successfully for negligence.

Trepass by invasive tree roots and/or overhanging limbs is one of the few forms of trespass to land where the law seems to condone a degree of self-help by the affected landowner. She is allowed to cut the limbs or roots at the property line without a court order. However, she must do so in a "non-negligent manner" in the words of a Court of Appeal decision on the topic. The court didn't go into detail about what that means, but most lawyers assume this means the trimming process musn't kill the tree or make it a hazard to fall over in a windstorm.

A court is unlikely to award any damages for trespass alone, i.e. just the presence of roots doesn't result in a compensable injury (she might be awarded a nominal $1 judgment). If, however, there is actual damage done, such as broken pipes or buckled pavement, the neighbor could sue and be awarded money damages.

It doesn't matter whether you planted the tree, or a former owner 50 years ago - it is your responsibility.

Courts usually dislike having to hear cases between neighbors over fences, trees, etc. It is much better for both neighbors to understand their rights and responsibilities and negotiate within the framework of that knowledge.

Often, it helps to get a written opinion from a licensed arborist as to matters such as what can safely be done to trim the roots, whether a particular situation is dangerous, etc.