Situation:
[Itan] and [ONE] were having a furball in Deneb B-12, which was Serco Unmonitored at the time. I (SolarFlare, +1000 Itani faction and -1000 Serco faction) layed a couple lightning mines near a clump of fighting. The lightning mines targeted and damaged both the Serco and my own teammates, even killing some after I layed some more.
I can only assume this has to do with the unique nature of lmines coupled with the hostile space, as FF restrictions still applied with other weapons.

If a hostile sets off lmines, they will target everyone in range (including friendlies, but not including the person that dropped them). Regardless of what sector you put them in. A friendly cannot trigger them, but if they are in-range of the mines when they are activated, they will get zapped.

Have you only just noticed this? o.O

In "Serco Space" even other itani appear hostile to each other which makes Itani L mines able to hurt friendly Itani. While places such as B-8 which are unmonitored and unclaimed L mines do not harm friendly pilots of the same nation.

Yoda is right. I once tested L-Mines with Niki in an empty sector in Ukari. We were both Itani with admire.
I dropped L-Mines and Niki turboed thru them.
Needles to say, his health went down to 5%.
I tested that long time ago on a ctc too. Dropped a few L-Mines in front of Itani ctc and they killed it. I got some faction penalty for that. :P

L-mines kill everyone but the person who dropped them.

I have never encountered that. I occasionally drop L-Mines right next to capships which my guildmates are entering, to prevent people such as Roda Slane from entering and shooting us while being invulnerable, and the L-Mines don't touch any Itani-admired Itani.

lmines probably "decide" who to attack based on the default VO friendlyness algorithm.

Goes something like so, assuming the lmine(mine_1) has default Itani faction standing, we're in Serco space, and the target in question(player_2) is an Itani with default standings

1. Make a variable that stores a number(val), set this to 0

2.¹ If player_2's standing with mine_1's faction is greater than Hate, then add one to val.
3.¹ If mine_1's faction standing with player_2 is greater than Hate, then add one to val.
4.¹ If player_2's faction standing with whoever local space is aligned with is greater than Hate, add one to val.

5. If val is equal to 3, then player_2 is friendly.

Now, step 4 is where things go strange. Walking through this, using default Itani standing for mine_1 and player_2 in Serco controlled space yields such:

1. val = 0
2. player_2 is liked by Itani, mine_1's faction; val = 1
3. mine_1 is liked by Itani, player_2's faction; val = 2
4. player_2 is in Serco space, and hated by Serco; val remains at 2.
5. val < 3, so player_2 is marked as unfriendly and mine_1 proceeds to zap the fun out of him.

In the case of Bojan's bit, I have no idea what was going on there. I've had combat with friendly lightning mines nearby with no issues several times before, and I don't think they've been changed significantly much since the last time I played with them.

¹If either of these steps don't yield a valid faction standing, just add 1 to val. For example, step three in Unaligned space.

Edit: I have no suggestions to add to this, only info.