In fact, I would argue that trying to set in place a system to decide between trivial and nontrivial inventions is more or less a waste of time because there will always be inventions that sit on the fence.
What patent law should achieve is purposefully vague - it's the ultimate subversion of the legal system for capitalistic purposes. The state is supposed to give exclusive rights over "ideas", in effect granting the monopoly of anything to anyone. Then the patent office is handed over the hair ball of defining what are "ideas", which ideas are worth a patent (aka "trivial inventions", as if such thing exists), or even which ideas are original (a joke in itself).
In my mind, we're asking the patent office to solve a philosophical problem, in the hopes they will sort out a logical conundrum caused by a vague law.
In practice, however, that's not important. What important is the economical function the patent office has. Which is, to use granted monopolies on order to incentivice inventions. It's fine if they give us a faulty answer the the philosophical conundrum we've charged them with, as long as the faulty answer furthers this purpose. That's a more measurable stick we can use. And I think by that stick, they are currently doing a much worse job than they could.
http://archive.mises.org/18812/andrew-torrance-patents-and-t...
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Patent systems are often justified by an assumption that innovation will be spurred by the prospect of patent protection, leading to the accrual of greater societal benefits than would be possible under non-patent systems. However, little empirical evidence exists to support this assumption. One way to test the hypothesis that a patent system promotes innovation is experimentally to simulate the behavior of inventors and competitors under conditions approximating patent and non-patent systems. Employing a multi-user interactive simulation of patent and non-patent (commons and open source) systems (“The Patent Game”), this study compares rates of innovation, productivity, and societal utility. The Patent Game uses an abstracted and cumulative model of potential innovations, a database of potential innovations, an interactive interface that allows users to invent, make, and sell these innovations, and a network over which users may interact with one another to license, assign, infringe, and enforce patents. Initial data generated using The Patent Game suggest that a system combining patent and open source protection for inventions (that is, similar to modern patent systems) generates significantly lower rates of innovation (p<0.05), productivity (p<0.001), and societal utility (p<0.002) than does a commons system. These data also indicate that there is no statistical difference in innovation, productivity, or societal utility between a pure patent system and a system combining patent and open source protection.
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Look at the criminal justice system. You can't always prove guilt or innocence in many trials, many times there are cases that sit on the fence but our system is set up with the assumption of innocence.