This phrase is frequently used by judges and lawyers: there are roughly 400 cases in CanLII which employ it.
Notable among them is R v Neil, 2002 SCC 70, where Binnie J applies a bright-line test to identify lawyers’ conflicts of interest.
We all know what this means (a test that is clear, easily applied and certain in outcome), but how did we come to use it?
The legal notion of a bright line seems to have its origin in Girard Trust Co v Commissioner of Internal Revenue, 122 F2d 108 (3d Cir 1941), where Goodrich CJ observes that ‘A bright line between that which brings conviction to one person and its influence on the body politic cannot be drawn’. The judge later says, ‘Nor has the law sought to draw such a bright line between the exercise of private and public influence.’
Justice Frankfurter referred a few years later to ‘a bright line dividing negligence from non-negligence’ (Wilkerson v McCarthy, 336 US 53 (1949)), which is probably where the concept takes off.
If readers are aware of any earlier citations, please share them!
Are lines actually bright, though? Perhaps if they are drawn in bright-red ink.
Or maybe the idea comes from physics, where a bright-line spectrum is a discontinuous one composed of lines resulting the radiation of an incandescent vapour or gas; or from photography, where a bright-line view-finder is one in which the area of the picture appears framed by a white line.
It’s unlikely, though, that US judges had these meanings specifically in mind in the 1940s.
In any event, the phrase has, over the decades, become a judicial (and lawyerly) cliché – like the safe harbors that US securities lawyers like to talk about, or the requirement for noisy withdrawal by a US lawyer from client fraud.
Clichés, while useful shorthand, are tired – and thus to be avoided by writers of lively, engaging prose.
Why not just say something like a clear test or a simple test instead?