There are three primary standards of proof in American justice system. These are (1) proof beyond a reasonable doubt, (2) clear and convincing evidence, and (3) preponderance of the evidence.
Proof beyond a reasonable doubt, which you may be familiar with if you ever watched a legal drama on television, applies only in criminal cases. It is the most rigorous burden of proof of three because someone's liberty (and sometimes life) is on the line.
In the civil context, either clear and convincing evidence or preponderance of the evidence apply depending on the particular legal question at issue. Clear and convincing evidence is less rigorous than proof beyond a reasonable doubt but is more rigorous than preponderance of the evidence. In order to meet the standard of clear and convincing evidence, the alleging party must prove their contention is substantially more likely than not to be true. Under this standard, the evidence must be substantially greater than a 50% likelihood of being true. This legal standard of proof is commonly applied in claims involving fraud, wills and inheritances, and critical family decisions such as removing a relative's life support.
On the other hand, the preponderance of evidence standard only requires that the evidence show that the allegation is "more likely than not" to be true. Put differently, the evidence need only show that there is a greater than 50% likelihood that the allegation is true.
In California, special education due process hearings apply the preponderance of evidence standard. What this means in practical terms is that the plaintiff, who has the burden of proof, typically, the child's parents in the vast majority of due process complaints, must convince the Administrative Law Judge ("ALJ") that it is more probable than not that the school district failed to provide their child with a free appropriate public education on the specific ground or grounds alleged (e.g., inappropriate placement) in the complaint.
That's the legal standard in a nutshell. But because it's so important, let's unpack the word 'preponderance' a little more. Preponderance relates to "the quality or fact of being greater in number, quantity, or importance." Not all facts are equal. And certainly not all testimony is afforded equal importance or weight by ALJs. In determining where the preponderance of the evidence lies with respect to a particular factual allegation, the ALJ will consider all the facts and circumstances of the case, including, but not limited to, witnesses' display of knowledge, credibility, and the nature of the facts to which they testify. What parents should aim for is a greater weight of credible evidence than the school district presents. This greater weight, on any particular fact, may come by the number, quantity, or importance of the evidence.
Preparing a case for due process hearing is challenging, to say the least. This is because to prepare properly, one must assemble the best evidence one has, identify one's weak evidence, and then anticipate what the school district will present in response as counterevidence and further make predictions about how an ALJ will view the evidence in totality when she makes a determination regarding what the preponderance of the evidence proves. The best practice, however, is to keep the burden of proof at the forefront and build your case around it so you have best chance of presenting the greater weight of credible evidence.
If you have a questions about due process hearings or special education in general, please feel free to contact my office. I'd be happy to help in any way I can.