You may call it self-harm, but I think we need to consider Britain's relatively pragmatic / less than enthusiastic membership of the EU. For a start, Britain has a completely different legal system to the rest of Europe (common law vs. civil law). That was bound to create tensions.
I don't see how you can make such a binary claim - UK vs "the rest of Europe". Your map shows 6 broad categories of legal systems in use across Europe. Even if you put the 5 non-common law systems into one bucket, it still wouldn't make the UK unique as Ireland operates under common law.
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