To Exclude Or Not To Exclude?

There are several reasons why the Board rarely grants motions to exclude evidence:

1. Weight, not admissibility.  The opponent's objections to the evidence usually go more to the weight to be accorded the evidence (i.e., how much it contributes to or detracts from a preponderance), not admissibility (i.e., whether a provision of the Federal Rules of Evidence bars its consideration).
2. Expert judges.The fact finders—administrative patent judges— are technically proficient legal professionals.  They are fully capable of sorting relevant evidence from irrelevant evidence and have no lay jury to shield from prejudice or confusion.  They generally treat the evidence for what it's worth.