Yeah, being lawful doesn't mean that you have to respect every law in the world. He said he planned to anticipate every possible option we could make in his campaign, but didn't expect for our almost all good party, three characters of which worship gods whose domains include freedom, to say slavery is bad.
There is the thought that it may have been partly to railroad us, but he is bad with alignments. I believe that I have mentioned the time he tried to force pvp in a different campaign that he was not even DM of. I gave our shaman permission to use an aoe spell that I was in the way of. He then jumped up and exclaimed that as a lawful character, I would be intolerant to friendly fire, and tried to force a fight.
Control freak DM. The worst kind.
I know because I'm quite sure I have been control-freaky on occasion, if I felt I was not controlling the story anymore. Especially when I was new.
Someone needs to explain to him that stories are made by DM's AND players. Sometimes, the story doesn't go the way it was planned, and it's not a bad thing.
Also he really needs to stop being a control freak. This isn't a videogame where you are mostly railroaded, this is a trip in another world. Let them explore.
Some limits are necessary (examples: PvP, relative power of characters and munchkinism) but arbitrary limits are very bad.
Or you can drop alignments. Alignments are a way to get all kind of personalities into nine descriptions, and it fails.
Really instead of alignment, D&D characters should have personality traits, flaws, and advantages, and they should be rewarded if they roleplay them well. Extra XP isn't a bad way if it gives an incentive for players to roleplay better and have a better story.
(person) doesn't know how alignments work, nor how LG can mean two different things in two different countries.
Edited for PC
Anyhow... Lawful Good can mean different things within the same country.
Yeah it is more then possible a Lawful Good person could be fully 100% in support of Slavery... It is also possible you wouldn't like it.
I personally think that Good can fight other Good on issues. The difference is that Good usually tries to avoid it.
True. Although a LG, if supportive of slavery, should at least give them a chance to go free, or at the very least treat them well.