We are in agreement as to the four levels being a better description of what takes place in the real world and better explains the levels of certainty a person will encounter. I agree that the way you describe the use exceeds the present description in 921 and does comply with the intent and sprit of the document. I look at 921 as I do all other NFPA documents as a minimum suggestion for an application with nothing saying a person can not exceed those requirements and still meet the intent of the document. I think even the terms you mention that are being used by other firms meets the intent of 921.

Patrick was attempting to get back into the document the idea of additional levels and with the public comments they receive I am hoping they follow his lead and adopt his suggestion.

Truthfully, I lean towards the terms "to a reasonable degree of scientific certainty" and "to a reasonable degree of engineering certainty" as being more descriptive as to the levels we should reach. This does not say the person is without doubt but does indicate he or she is well above 51% presently being called for with the use of “probable”. It just sounds more professional. This is just my thought to elevate the level of our professional appearance to those out side our industry.

As it stands now, a good attorney could twist the wording from the definition of the word “probable”, and if the investigator is not well versed and able to articulate his or her thoughts on the subject will have their opinion degraded to the point it may be correct but still not accepted by the trier of fact. You know most attorneys are taught if the facts are correct then attack the person giving the facts. More and more we see attorneys attacking the creditability of the investigator and not the facts behind his or her opinion.