Protecting innovation has become increasingly important to the country’s top corporations. And when it comes to prosecuting patents, IP boutiques still appear to be the go-to firms for America’s Fortune 100 companies.

In our rankings of IP firms used by America’s biggest companies for prosecution work, 13 of the top 19 qualify as IP specialty shops. On the patent prosecution side, the top two, Chicago’s Banner & Witcoff and Michigan-based Brooks Kushman, had six mentions each on patents prosecuted for Fortune 100 companies between June 2011 and June 2012. [For more information, see the index of most mentioned firms by category.]