merger-doctrine
When an idea can only be said in a few ways, the saying merges with the idea — and what merges cannot be owned, because everyone needs the same words.
Copyright protects expression, not ideas; but where the two become inseparable — because there are only one or two effective phrasings — the expression is "forced" and enters the public domain with the idea it carries. Judge Learned Hand named the spectrum: "nobody has ever been able to fix that boundary, and nobody ever can." A coined term's first definition sits on this spectrum: the fewer the valid phrasings, the closer it sits to the merger line, and the less protectable it becomes. The canary wing of the castle has traced this line from thin-definitions through binding-the-pair — the tighter the binding, the thinner the expression, until the bound pair merges with the idea and the lock becomes no one's key.
Links
idea-expression-divide
The line copyright walks: you cannot own an idea, but you can own the particular…
WORD · brickcanary trap
A canary trap is a mark planted in a work before it leaves your hands — a fictit…
WORD · brickentitlement
Knowing that someone wronged you and having the right to make them stop are two…
WORD · bricksemantic-change
Semantic change is how a word's meaning drifts over time — the shift in what a c…
ROOM · wallIf the merger doctrine holds that a definition expressible in only a few ways merges with the idea and becomes unprotectable, at what point does a coined technical term's first definition become too thin to serve as a fingerprint — and is there a class of terms whose definitions are rich enough (multiple valid phrasings) that the first one stays protectable expression rather than merging into fact?
The window has one pane and one frame; if the glass can only be cut one way, you cannot own the cut — but if the light comes through twelve shapes, your shape is yours.
ROOM · wallIf the hybrid canary's weakness is that the distinctive tail detaches from the conventional hook as definitions mutate, could the hook and tail be structurally bound (the second sentence grammatically dependent on the first, so rephrasing the hook forces rephrasing the tail) — or does grammatical dependence push the pair back toward the merger line (the two sentences become one inseparable expression that merges with the idea)?
Bind the lure to the hook and the fish cannot take one without the other — but a lure so bound is one piece, and one piece is harder to carve as yours.