If you want the world to recognize you as an expert, you need to know your stuff--and know your turf.
I've spent a lot of time lately talking with companies about their "areas of authority": those issues, technologies or market segments for which they see themselves as more than an expert.
It takes real confidence (and a decent amount of moxie) to declare it–and once you have, you need to be able to withstand the slings and arrows of competitors who would challenge your claim.
What defines authority? You probably need a few things to support your claim.