This question is particularly challenging because of its connotation that a certain response time may be legally defendable. To the best of our knowledge, there is no law that defines or establishes response times for emergency services. Thus, the question may be better framed to determine if a particular response time to an emergency raises a claim of misfeasance, malfeasance or nonfeasance of duty.
Misfeasance – Taking an action determined to be inappropriate, even if with good intent. (Example: A response time is deemed to be too long by a plaintiff even though the fire department was operating to the best of its abilities.)
Malfeasance – Taking an action that purposefully results in harm. (Example: A response time was delayed because the members were engaged in a softball game and decided to finish the inning before responding to the emergency.)
Nonfeasance – Taking no action at all when a prudent person otherwise would have (Example: The fire department did not respond at all because there have been too many false alarms to that address in the past.)
We must make it clear that we are not attorneys. Thus, asking an attorney questions about response-time liabilities would be prudent. Ask several attorneys and you’re likely to get multiple opinions. It would be smart to get your legal opinion from your town or department attorney because he or she will be the one providing the defense if a legal challenge is raised about response times or failure to respond in a timely manner.
What about the evidence for a response-time standard? Unfortunately, the empirical evidence is somewhat limited. Most responders possess anecdotal evidence, gathered through years of experience while responding to emergency calls. Armed with this experience, responders know a quick response makes a difference in the outcome.
Some scientific proof of fire growth does exist, however. The National Institute of Standards and Technology (NIST) has modeled fire growth for multiple scenarios, including incidents where firefighters were killed. These videos can be found on YouTube using the search terms “NIST fire modeling video” or “NIST flashover video.” NIST has also measured and graphed fire growth using devices that track heat generation over time. NIST’s work provides solid evidence that fire, left unchecked, will grow exponentially as it consumes the contents of a structure.
Fire departments with quick and appropriately staffed responses to fires (assuming the fires are reported early and efficiently) have a better chance of saving lives and reducing property damage than a department whose responses are slower. The fire growth charts support this. But where is the evidence that supports what a response-time goal should be? Unfortunately, this is where the empirical data falls short. It has not been proven, scientifically, the difference in outcome when a response time is four minutes versus five minutes versus six minutes versus 10 minutes.
Several videos are available that help demonstrate the results of time delays. These can also be found on YouTube. First is a video created by Underwriters Laboratories (UL) demonstrating the differences in legacy contents versus newer contents in homes. In this video, the UL team lights two fires in mockups built side by side and show fire progression. In the modern-contents mockup, flashover occurred in three minutes, 40 seconds. In the legacy-contents mockup, the flashover takes 29 minutes, 25 seconds to occur. Search “New vs Old Room Fire Final UL” for this video.
Second are the many videos created by fire departments across the U.S. during fire sprinkler demonstrations. In these videos two mock rooms are set on fire. One of the rooms has a sprinkler system and the other does not. The difference in fire progression and damage is significant. Search “Home fire sprinkler demonstration” for these videos.