A pro per can cross-x the rater. You can do almost anything a lawyer can do in the law with very few exceptions.
Remember that the rater was rating from instructions given to him/her by the trial judge. She's basically just a translator. If your problem is with the instructions, that's not subject to cross-x. So you are objecting to the translation. The rater does noting all day long but rate reports. She's a pro. She's an all-star. The judge relied on the rater even though the law says that the judge is a rating expert just by being a judge. You had better know the rating language better than the rater if you hope to have any chance of succeeding. Most attorneys get nowhere with a cross-x of the rater.
In the en banc decision, Blackledge v. Bank of America, the Workers' Compensation Appeals Board delineated the respective roles of the evaluating physician, the workers' compensation judge, and the DEU rater when determining ratings under the AMA Guides. I suggest you read this: http://www.dir.ca.gov/wcab/EnBancdecisions2010/Blackledge.pdf
While you can cross examine you still have to have the right questions to get the point across. I suggest you look at Ms Harris video and then decide if you need to talk to an experienced workers compensation atty near you for advice.
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