The foundation of American law is the assumption of innocence, because one of our country’s core principles is the idea - and reality - of freedom. Because personal liberty is so important, a defendant charged with a crime is presumed innocent throughout the trial. The burden is on the prosecutor to prove guilt beyond a reasonable doubt, a traditional standard of proof. Since proving the crime may result in loss of the defendant's liberty, the prosecutor must have evidence that proves guilt. All the defense has to do is sow doubt in the prosecutor’s case by proving an alibi, questioning the prosecutor’s witnesses’ observations and conclusions, and/or providing defense witnesses for support of the defendant’s version of the story.
If there is not enough evidence to prosecute a crime, an injured party may file a civil lawsuit, suing the defendant for damages, return of property or other remedies. The burden of proof is lower in civil cases, because the loss will be economic in nature and will not result in a loss of freedom. Civil cases are won by proving a claim by a “preponderance of evidence” or “clear and convincing evidence”. A preponderance of evidence is often defined as “more likely than not”, while clear and convincing evidence can result in punitive damages. Clear and convincing evidence is a higher burden of proof but still lower than “beyond a reasonable doubt”.
Animal-related crimes are often difficult to prove “beyond a reasonable doubt,” especially when they occur behind closed doors. This is one of many factors that prosecutors must consider when bringing charges in response to a crime against animals.