Controversy can be localized, particularly in the years before the rise of the internet. That meant some surprisingly popular shows like Star Trek end up causing far more of an uproar elsewhere in the world than they might in North America, where the franchise has traditionally been filmed. In fact, while Star Trek: The Next Generation, Season 3, Episode 12, “The High Ground” was a pointedly political episode, a throwaway line of dialogue led to it being banned in both the UK and Ireland for decades.
The controversy around "The High Ground" stems from one line about a hypothetical reunification of Ireland. But owing both to the context of the episode -- examining the lines between terrorists and freedom fighters -- and the era in which it aired, the BBC and RTE pulled it before it could air. The issue is still too heated for the latter to air it, and the former waited the better part of two decades before finally putting it on the air.
“The High Ground” concerns itself with separatists on a neutral planet who kidnap Dr. Crusher and demand her help to cure a mysterious ailment afflicting their fighters. In and of itself, it was a competent but largely unexceptional episode, and according to Captain’s Log: The Unauthorized Complete Trek Voyages, producers Ronald Moore, Brannon Braga and Michael Pillar were all dissatisfied with the way it turned out. It had little to say on the subject it purported to cover, and feels very timid in light of most aggressive explorations of the same themes on Star Trek: Deep Space Nine. As a filler episode, it’s functional, but it does little more than mark time otherwise.
That wasn’t what caused its virtual banishment in the UK and Ireland, however. The controversial line in "The High Ground" comes from Data, who points out that the separatists' tactics echo similar insurgencies in Earth’s history. He specifically cited “the Irish Unification of 2024” as an instance when such tactics succeeded in effecting political change. The line was presumably intended as a little world-building and a way of connecting the drama in the story with similar issues in the contemporary world, and while it passed with no issue in North America, the BBC and RTE saw it much differently.
The episode aired in January of 1990, when Margaret Thatcher was Prime Minister in the United Kingdom and her government had taken a hard line against the IRA for over a decade. The Troubles were raging at that point, and IRA attacks on British soldiers in Northern Ireland were common. So, in light of that environment, the episode was simply pulled from the roster before it aired, lest it inspires acts of violence.
And it remained off the air for 17 years, only airing on the BBC for the first time in September of 2007. To date, it still hasn’t aired on RTE, and while that doesn’t hold as much weight with today's media landscape, it's still a significant stand against the episode's content. VHS copies were released in the UK throughout the 1990s, but were limited to two or three episodes per tape and usually intended for hard-core fans. That way, without having a broadcast airing, millions of people would miss it entirely.
The episode presented the issue in a cavalier fashion, and that made the decision easy to stand by. The slow creep of media overtook it, and today, even RTE’s continued refusal to air it probably means little in practical terms. But at the time, it was a sign of how powerful such stations could be when they wanted to and how easily they could remove something they objected to. It’s also a reminder that, even when its efforts didn’t always meet the standard it set for itself, Star Trek has always tried to engage in social issues, for better or worse.