Every lawyer should have a passing familiarity with rules of evidence. If nothing else, it's required studying for the bar exam. Trial lawyers, though, must have a thorough grasp of core evidentiary rules. The stress of a looming trial is not the time to be re-memorizing common objections to witness testimony, as just one example.
Rules vary according to jurisdiction, of course, and the application of those rules will vary according to the presiding judge. Still, many core principles are consistent.
FindLaw provides conscise, easily digestible summaries of rules of evidence, including types of evidence, common objections to testimony, and a crash course on hearsay and its myriad exceptions.
Been awhile since you've brushed up? Coming to rules of evidence for the first time? Start with our summary of evidence rules.