THE FLC FAILED TO COMPLY WITH THE ALT RESTR.

Narrative

ON DSCNT FROM FL310 FOR LNDG AT OHARE; ZAU CLRED US TO CROSS 45 NM SE OF ORD AT 11000 FT MSL; 250 KTS. THE CAPT WAS FLYING THE ACFT AND OPERATING THE FMS. I OBSERVED HIM PROGRAM THE XING POINT AND ENTER THE AIRSPD AND ALT RESTR 'IN THE BOX.' I WAS SOMEWHAT PREOCCUPIED WITH RUNNING CHKLISTS AND GETTING THE ATIS AND DID NOT NOTICE THAT HE INADVERTENTLY PUT THE ALT RESTR OVER ORD INSTEAD OF THE POINT 45 MI SE OF ORD. AFTER I FINISHED MY OTHER DUTIES; I SELECTED THE DSCNT PAGE ON THE FMS AND NOTICED THAT THE VNAV DSCNT WAS SHOWING US REACHING OUR XING ALT ABOUT 24 MI SHORT. THAT SEEMED STRANGE AND SHOULD HAVE REGISTERED IN MY BRAIN TO START CHKING THINGS; BUT IT WAS THE CAPT'S LEG AND HE SEEMED TO HAVE EVERYTHING UNDER CTL. ZAU CALLED AND ASKED IF WE HAD RECEIVED OUR CLRNC TO CROSS 45 SE OF ORD AT 11000 FT. THE TONE OF HIS VOICE GOT OUR ATTN AND A GLANCE AT THE FMS SCREEN SHOWED WE HAD ABOUT 2 MI TO GO TO THE XING POINT AND WE WERE JUST PASSING 19000 FT! THE CAPT EXTENDED SPDBRAKES AND BEGAN A MAX SPD DSCNT; BUT WE WERE STILL ABOUT 7000 FT HIGH AT THE XING POINT. WE GOT AN OFF COURSE VECTOR FROM CTR AND FINISHED OUR DSCNT UNEVENTFULLY. I WOULD NOT HAVE FIGURED OUT EXACTLY WHAT HAPPENED IF THE CAPT HAD NOT TOLD ME LATER THAT HE PUT THE XING RESTR OVER ORD INSTEAD OF THE XING POINT ISSUED BY ATC. I THOUGHT THE FMS HAD JUST MISCALCULATED FOR SOME UNKNOWN REASON. SOME FACTORS SURROUNDING THE SIT. I HAVE ALMOST 4000 HRS OF FMS FLYING AND AM VERY COMFORTABLE WITH IT. MOST CAPTS HAVE EVEN MORE EXPERIENCE THAN I DO. I THINK I GOT COMPLACENT AND ASSUMED THE OTHER CREWMEMBER HAD THE SIT IN HAND. IT WAS ALSO THE FIRST LEG I HAD EVER FLOWN WITH THIS CAPT. I HAD BEEN CALLED OUT SHORT NOTICE FROM RESERVE TO FILL IN FOR HIS SCHEDULED COPLT. I SHOULD HAVE BEEN MORE ATTENTIVE TO HIS ACTIONS UNTIL I HAD A BETTER FEEL FOR HOW HE FLEW THE ACFT; AND EVEN THEN SHOULD HAVE BEEN READY TO BACK HIM UP. THE WX WAS BEAUTIFUL AND CONTRIBUTED TO THE SENSE OF WELL BEING AND BOTH CREWMEMBERS' COMPLACENCY. THE TASK ASSIGNED BY ATC WAS SIMPLE AND SHOULD HAVE BEEN EASY TO ACCOMPLISH. THE CAPT JUST DIDN'T PAY ENOUGH ATTN TO MONITORING THE ACFT AND I DIDN'T BACK HIM UP.