Although as a temporarily solution this is reasonable, I think what would be better is that if you hit them; then there should be a 5s with a "Hey what are you doing!?" message pop-up where if you hit them again THEN you get Fined providing some leeway in terms of accidental shots against anyone (NPC, Security or Players) prior to getting the Fine.
It also would make sense if Fines were just that, where you are only being Fined within that given System but there is no "Wanted" attribute; it is only if you refuse to pay the Fine for say 1hr that it become a Bounty.
This isn't to say that should someone shoot you (even accidentally) then you shouldn't get Combat Rights without Security being notified. This would be the point in them changing from Green to Red on the Scanner, indicating 'Free to Shoot' Targets. In-fact this could extend to say when you become Friendly with a Faction your 'Fines' are reduced, and if you become 'Allied' then you get a "Marque of Piracy" (given you purchase it from the 'Local' Authorities from the Contacts list) that then means attacking ANYONE who is not also Allied with them regardless of "Wanted" is no longer considered a Crime.
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These would of course be potentially pricy depending on the System Security (Higher would mean more Police to "Bribe") but would allow you to operate semi-under the banner of a given faction you've chosen to support. It could also include how the Local Security treat you, where as it is right now quite common for Security to actually open fire on you even IF you're not wanted and only been going after Wanted individuals; simply because you have your Weapons out or killed someone.
So if they were friendly enough, then they would basically turn a blind eye to you this behaviour.
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I also think that in order to make sure Bounty Hunting is a bit more worthwhile, there should also be the option of a 'Bounty Hunter License' again available from the Contacts, and Faction Dependant (so only valid for the local faction) with the price being set by again how much they like you (but should be EXPENSIVE) where if you K-Scan someone and they have a Bounty from a different Faction that this then marks them as a 'Valid' target for you holding that License.
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The final thing I would suggest is allowing Bounties to be Paid in Space, for example when you're interdicted by local Security; they as you to "You have outstanding Fines. Shut down your Engines and prepare to be Boarded", where if you stop; you can then highlight one of the Security via 'Contacts' and clicking them as with Docking would provide the option to "Pay Local Fines (Amount Cr)", rather than them simply opening fire immediately. Not complying with their demand within 10s, activating FSD, Weaponry, etc... would instantly result in a Firefight.
The same could be done for Contraband Cargo, where provided you dump the Cargo for the Authorities to Scoop; then will only Fine you rather than attacking you.
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I mean the obvious idea is to temper back the Police, with reasonable options rather than the Captain Kirk "Shoot First, Ask Questions when they're Dead" situation we have right now; as there are no doubt a few of us here who have accidentally run afoul of the law without ever intending to simply because they're just so damn vicious. As if the Police shoot at me for no reason at all, why the heck is it criminal for me to then defend myself? Let alone have no ability to simply Bribe them (which was in Frontier/FFE)