The following is from IRS Publication 535, Business Expenses, page 44.

"You can also deduct [as business expenses] the cost of your own education (including certain related travel) related to your trade or business. You must be able to show the education maintains or improves skills required in your trade or business, or that it is required by law or regulations, for keeping your license to practice, status, or job. For example, an attorney can deduct the cost of attending Continuing Legal Education (CLE) classes that are required by the state bar association to maintain his or her license to practice law.

"Education expenses you incur to meet the minimum requirements of your present trade or business, or those that qualify you for a new trade or business, aren't deductible. This is true even if the education maintains or improves skills presently required in your business."