Are there any laws of memory? Several years ago, my adviser wrote an article discussing the observation that a hundred years of studying memory had not resulted in the discovery of a "law" of memory. He wrote (p. 247):


  When one reads or hears the claim that “repetition improves retention”
  or that “generating information enhances recall” or that “forgetting
  follows a power function” or all other statements of the form that
  “variable X has a consistent effect on variable Y,” one can be certain
  that the claim is both true and false. It is true in that conditions
  can be found under which the rule holds (otherwise the claim would not
  be made), but false in that a skeptic can always say: “Very nice work,
  but your ﬁnding depends on many other conditions. Change those and
  your effect will go away.”


Has the story changed since 2008? Can anyone cite a proven true law of memory? If not, what's the closest thing memory has? The idea of transfer-appropriate processing is the closest I can name, is there something more substantial?
Memory is only a psychological construct. In reality there is only the brain, and the physiological functions of the brain. "Memory" is just a way to conceptualize some of these functions. For this reason, it's unlikely that a law will ever emerge. Part of the reason is that memory can refer to so many different things, biologically. 

Even when you get down to the actual biology, laws are not really the standard. Biology is a messy thing and virtually no laws exist that couldn't be contradicted. Something as basic as the cell theory could be reasonably argued against. Viruses are not cellular, yet an argument could be made for them being alive. It isn't the current thinking, but it's not an absurd proposition either. If psychological phenomena are a result of biology, and no laws exist in biology, I think it's reasonable to say no laws will exist in psychology either.

Perhaps one of the strongest ideas about memory is Hebbian learning. But even that is just a simplification.