A judge Monday ruled to drop some charges against the Holbrook man accused of driving drunk and killing a Boy Scout.

Four of the 16 charges Thomas Murphy faced have been tossed out.

The judge says they're no longer "legally sustainable" because they relied on Murphy's blood alcohol level being above .18.

Murphy's lawyer argues a witness for the prosecution didn't hand over all his notes about Murphy's BAC the day of the crash.

Murphy is accused of driving drunk and killing 12-year-old Andrew McMorris last year.

McMorris' mom says what happened today is a terrible display of the loopholes in the system. She says what's happening in the courtroom is a disgrace to her son's death.

Following the judge's ruling, the defense then called its first witness.

Dr. Jimmie Valentine, a forensic toxicology expert from Mississippi, testified that Murphy's blood alcohol level taken from a blood test hours after the crash could have been contaminated.

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