From the CBA:
Domestic Block Hour Limitations
1. A pilot shall not be scheduled as an operating crew member in excess of 8 block hours during a single duty period or during any consecutive 24 hour period, except as provided in Section 12.C.2.b.
2. A pilot may be scheduled as an operating crew member to exceed 8 block hours during any 24 consecutive hours. Prior to exceeding 8 ABH in that period, however, he shall have received an intervening legal rest period of twice the block hours flown since his last legal rest period, or 9 hours, whichever is greater, except as provided in Section 12.C.2.c.ii., or iii.
3. A pilot originally scheduled under Section 12.C.2.a., or b., but who, due to headwinds, ATC delays or other unavoidable circumstances (including an intermediate stop for these reasons) is projected to exceed the limitations contained in those paragraphs, may continue to the extent permitted by FAR regulations. Duty time and rest limitations as provided in Section 12.C.5. and C.6. still apply.
1. A pilot who, due to headwinds, ATC delays or other unavoidable circumstances (including an intermediate stop for these reasons) is projected to exceed 8 ABH without an intervening legal rest period, shall be permitted to continue to base or to his layover station, whichever is scheduled to occur first, at which point he shall receive a legal rest period. However, a crew shall not block-out from a location after having exceeded 8 hours of block time in a 24 hour period without a legal rest period.
2. If a pilot is originally scheduled to exceed 8 block hours in 24 consecutive hours, as provided in Section 12.C.2.b. (above), but due to headwinds, ATC delays or other unavoidable circumstances (including any intermediate stops for these reasons), cannot receive the minimum required legal rest period, the following shall apply:
(a) he may be rescheduled for a legal rest period of at least twice the block hours flown since his last legal rest period, but not less than 8 hours; or
(b) his schedule may be revised to not exceed 8 block hours in 24 consecutive hours; or
(c) he may be replaced (and shall earn trip guarantee).
3. If a pilot departs his base on a flight and makes an unscheduled return to that base without an intervening stop and he is then projected to exceed 8 block hours in that same duty period, the Company shall employ one of the following options:
(a) reschedule the pilot so as not to exceed 8 block hours; or
(b) schedule the pilot for a legal rest period at base to ensure future legality; or
(c) remove the pilot, and, if he is not a MUV, MUS, CMU, AFB, VLT, or DRF pilot, he shall be eligible for substitution; or
(d) remove the pilot, and, if he is a MUV, MUS, CMU, AFB, VLT, or DRF pilot, compensate him the greater of 3 CH, ABH or duty rig computed from his scheduled showtime until his actual release.
As usual, the company stated what is allowed by the FARs, but left out what is in the contract. Legally, you could agree to what the company stated, but it would be like flying a DP, or waving your 1 in 10. (Giving up what the union has worked to achieve in order to protect the crew's safety.)