A minefield is created by a new ship component called the minelayer. Another ship component called the minesweeper is used to remove the mines. The mine layer would automatically lay the best mines researched in the weapons tech. This could either be a new line of tech, or just become a ship part that comes with each new tech(phaser, disrupter, etc). The mines would have FoF(Friend or Foe) recognition and not target allies nor the race that layed them. Consequences of the minefield could be damage to the ship. Larger ships having a harder time avoiding the mines, smaller ones having a better chance. The amount of damage is based on the size ship + tech of the mines + speed of ships. If the minefield is "seen", then the option is given to reduce speed to 1 which reduces damage to ships. All minesweepers move at speed 1(1 pc/turn) through minefields. If the minefield is unseen, then speed is normal.

A new option is added to the ship/fleet screen that allows the players/AI to set the speed of the fleet, defaulted to the speed of the engines. If entering known enemy space and they are known to use mines, then set the speed lower to lower damage to the fleet if we can't see the new mines.

Scanner technology becomes more important as higher scanners will be needed to be placed at least on one ship in the fleet to see the mines as the technology of mines increase.

Minelayers can lay mines in 1 pc at a time and have a build time similar to building on asteroids.

New UP laws forbidding the mining of trade routes.
New UP laws forbidding the mining of space outside your area of influence.

Minefields decay after so many weeks(say 52).
Minefields are removed after so many attempts at taking out ships(3-5).
Minefields are upgraded in 1 turn by having the minelayer revisit the minefield or perhaps be automatic.

Brian Pleshek