CAPT OF A BA32 JETSTREAM OVERSHOT RWY HOLD SHORT LINE DURING TAXI TO PARKING CAUSING NEAR CONFLICT WITH ANOTHER ACFT TAKING OFF ON THE ACTIVE RWY. FLC WERE BOTH DISTRACTED DUE TO A L BRAKE PROB.

Narrative

AFTER A NORMAL APCH AND LNDG TO RWY 16; THE ACFT DECELERATED ON THE RWY AND A NORMAL XFER OF CTLS WAS MADE. AS THE ACFT WAS SLOWED TO TAXI SPD; THE CAPT STATED HIS L BRAKE PEDAL WAS NOT FUNCTIONING NORMALLY (LESS THAN 100% EFFECTIVE). AS WE TAXIED CLR OF THE RWY; THE TWR GAVE US TAXI INSTRUCTIONS VIA TXWY A; HOLD SHORT OF RWY 11; AND CONTACT GND. I READ BACK THE CLRNC AND THE CAPT ACKNOWLEDGED IT BACK TO ME. AT THIS POINT THE CAPT CONTACTED GND WHILE I LEFT THE FREQ TO CONTINUE WITH THE NORMAL AFTER LNDG DUTIES (IE; RECEIVE GATE ASSIGNMENT; CALL COMPANY; GIVE PAX ARR BRIEF; AND COMPLETE CHKLISTS). MEANWHILE; AS WE TAXIED ALONG TXWY A TOWARDS RWY 11; THE CAPT WAS 'TESTING' HIS BRAKES; ATTEMPTING TO TROUBLESHOOT THE PROB; IN AN EFFORT TO GIVE MAINT AN ACCURATE DESCRIPTION OF THE PROB. WHEN I FINISHED THE ABOVE MENTIONED DUTIES; I STATED THAT I WAS BACK (MONITORING THE #1 COM). AT THIS POINT THE CAPT INSTRUCTED ME TO TEST MY BRAKES TO ASSIST WITH THE TROUBLESHOOTING. SUDDENLY WE BOTH REALIZED THAT OUR ACFT HAD CROSSED THE HOLD LINE FOR RWY 11 AND THAT THERE WAS ANOTHER ACFT DEPARTING THAT RWY. WE WERE ABLE TO STOP SHORT OF THE RWY EDGE; BUT WELL BEYOND THE HOLD LINE FOR THE RWY. THE ACFT ON RWY 11 DEPARTED WITHOUT INCIDENT. OUR FIXATION ON THE BRAKE PROB AND INAPPROPRIATE PRIORITIZING OF TASKS ALMOST LED TO WHAT PROBABLY WOULD HAVE BEEN A VERY SERIOUS ACCIDENT.