In my business experience, innovation is only possible when everyone in the team is prepared to share their divergent thinking - without fear of judgement, labelling or future retribution.
The essential elements are trust and the preparedness to initiate challenging conversations while also being prepared to "be" challenged. This type of interaction can get very messy which is why constructive and courageous leadership is essential as is an agreed terms of engagement - focussed on the people and the task.
Expect conflict, expect to be challenged, expect your heart to pound as you initiate a challenging conversation - expect discomfort - as everyone is encouraged to shift into their learning zone. Without this we don't innovate!