Recently, North Carolina put it to a vote, in a primary election, whether or not to amend its state constitution to define marriage as between a man and a woman only. There are any number of problems with how this was done.
The first big problem was with the issue that this was a primary election. For those not familiar with the US political system, it's generally accepted that party nominees for the election proper should be selected by voters, on the grounds that this will produce candidates that are actually electable. This is less and less the case, as in a primary the candidates are generally only voted for by those who have declared the appropriate party preference. This leads to each party producing candidate who stridently blare their own party line, and having no incentive to nominate anyone who's willing to work with the other party. The other issue is that typically, the party of the incumbent will have little incentive to vote in a primary. In California at least, nobody in the Democrat party is standing against Obama for the Presidential nomination, and so there's little incentive for registered Democrats to actually get out and vote. Turnout is always lower in primaries than in elections proper.
So this was put to a vote of "people who care" in an environment likely to be tilted towards Republicans; the Republican party having firmly nailed itself to the position that gay people don't deserve to get married. This is already set up to produce extra votes for a ban.
Then we get to the language of the bill itself. It doesn't actually do anything to gay marriage, which was already not recognised under North Carolina's state law; what it does do is strip any long-term relationship which is not a marriage between a man and a woman of legal recognition. Any domestic partnership, civil union, call it what you will, if it's not a marriage, it now has no legal standing in North Carolina. This does horrible things for anyone raising kids with someone they're not married to; it does horrible things to protection from domestic violence; it does horrible things to evidentiary standards for stalking. It's sickening how many legal protections it strips from the heterosexual couples it claims to be protecting (and protecting from what? As far as I can tell, protecting from having to admit that not everybody falls in love the way you do).
So it was set up unfairly, and it does bad things to good people. What else? Well, it stated in its definition that it merely required a simple majority to pass. What that means is that of the people who voted regarding it, 50% plus one person would be enough to pass it. Frankly, for a document with paramount status, this is ludicrous. 50% of the electoral turnout, in a primary, can be a tiny proportion of the actual population of a state. I'd be more satisfied with requiring that 50% plus one of registered voters be needed, regardless of turnout. Of course, the ideal would be that human rights not be up for popular vote.