Why are Babylon 5 security forces provided such dangerous weapons, like the PPG for civil duties?

Question

The "PPG" hand weapons used by Babylon 5 security seem to result in an inconveniently high body count.

On several occasions defensive use of a PPG results in the death of an assailant, closing off an important line of inquiry and arguably an unnecessary loss of life.

Assuming Garibaldi prefers captives to corpses and has trained his department as well as he claims we must ask if the tool is at fault.

Is there a specific reason in-canon why civil security forces are provided a weapon with such a low survivability?

Examples updated as i find them:

S2-Ep14 "There All The Honor Lies" 02:30 - Sheridan is set-up and defends himself against a Minbari with a standard PPG. Although the weapon is left for him as part of the setup it appears to be a standard PPG, familiar to Sheridan and killing the Minbari leaves him in considerable jeopardy

S3-Ep12 "Sic Transit Vir" 22:25 - Despite having the upper hand Zack Allan one-shots a Narn armed with a knife leaving the Narn's motive a mystery.

Perhaps Unit 5 of the B5 Security Manual could shed some light if anyone has a copy?

Answer 1

Phased Plasma Gun is a type of weapon that fires a bolt of energized, super-heated helium sheathed in an electromagnetic field and propelled by an opposed magnetic field. On impact, the plasma bolt dissipates and discharges its thermal and kinetic energy^[1].

So projectiles from a plasma weapons are not going to make hull breaches and are only harmful to a biological entities.

Standard Settings of Auricon PPG^[2]:

Low – twelve shots
Standard – seven shots 
High – four shots

With a lower-level PPG the shot will normally burn and cauterize a wound, leaving the target down but alive^[1].

They are issued for same reason that police have guns on Earth.

Answer 2

Although you say that Babylon 5's security team are a "civil" security force, remember that while the space station is in "neutral territory" between the 5 empires it was a joint project between the members of the Interstellar Alliance. In-universe, the station was granted a "military and operations budget" from the Alliance during the years it was attached to them, so although independent, its security was considered to be "military" rather than "civil".

Having said that, if you consider the station to be completely independent of the Alliance due to its peace-keeping mission and entirely non-militaristic, there are real-world comparisons to be drawn to the United Nations Peacekeeping army. Troops serving in UN peacekeeping operations carry light weapons and are allowed to use minimum force in self-defence, or if armed persons try to stop them from carrying out their authorized tasks. "Light weapons" covers pretty much any hand-held gun, so all the lethal ones. Plus that's just what troops can carry - the UN also have tanks in their arsenal! So if a real-world peace-keeping army carry lethal weapons it isn't really a surprise that the security force for the "last, best hope for peace" carry them too.

Meanwhile, back in-universe... I'm not sure that the alternative of non-lethal weapons would even work against the massive variety of life-forms that come aboard the station. A stun device - the equivalent of a real-life taser - capable of stunning one species could be potentially lethal or even ineffective against another. It makes sense then that they carry lethal weapons but follow a code of ethics on how and when to use them.