This is a grey area from my experience because:
01. Depends on the contract conditions. Most used contracts have a specific period during which the Client/Engineer/Consultant has the right to comment/reject the schedule. After this period the submitted schedule is approved by default, if the Client/Engineer/Consultant did not make comments/reject the schedule.
02. Depends on the contract conditions. Is the Contractor allowed to start work if the baseline is not approved?
03. Good faith of parties, that governs all contracts. It is not of good faith in a contract for the Client/Engineer/Consultant not to comment/reject on a baseline schedule for 6 months (as an example) after the work has begun, just because he has no contractual time period to do so. Also if Client/Engineer/Consultant did not instruct the Contractor regarding the execution, for 6 month (as an example), (denial of execution of certain activities, for example); then how can the Client/Engineer/Consultant say he did not approve the schedule?
From my point of view the baseline schedule belongs to the Contractor, it just a transparent way to show how he will do the work. It is not the purpose of the schedule to let the Client/Engineer/Consultant dictate to the Contractor how to do the work; by this logic the Client would to the work without the Contractor.
Best regards,
Bogdan