I'm curious what time frame that study covers? Since the summary mentions that they started with 800 lethal force situations, it must go back quite far.

As moral beings, it's a good thing that these officers hesitate to use lethal force, unfortunately, in a lethal situation, that can get you killed. But I wonder if the situation has actually been changing in the last decade compared to the report's findings?

I say that because law enforcement has increasingly become "militarized" since 9/11 and the traditional police vs military mindsets are very different. Not only in terms of firepower and tactics, but even the officers themselves have changed. Many vets from Iraq/Afghanistan have joined police forces, and many police officers were called up to deploy, so these officers have combat experience that most officers in the 80's or 90's probably did not experience.

A combination of the "war on terror" and increasingly violent events along our Southern border by Mexican drug cartels, in addition to the wider "war on drugs" seem to have triggered this sea change in American policing. Extra funds devoted to police forces for these purposes have given them the means to buy all kinds of potent weaponry, pay for SWAT teams, pay for more elaborate training, etc. The extreme example is NYC after 9/11 where beat cops were suddenly supplemented with heavily armed officers with helmets, body armor, and automatic weapons openly patrolling public spaces, like busy Grand Central Station and other venues. Another visible example of this change is the increasing use of SWAT teams to serve more and more search or arrest warrants, in scenes reminiscent of soldiers "stacking up" and kicking in doors in Iraq or Afghanistan.

Like that FBI report, the US military noticed a long time ago that a great many soldiers would not fire directly at enemy soldiers. They would not fire their weapons or would deliberately miss. In response, the military devised training methods to try and override that tendency. If more and more of our police officers have had that training, plus actual combat experience, it stands to reason that fewer officers will hesitate to pull the trigger now compared to 10-15 years ago IMHO.