Is Condo Board Levying fees illegal?

My condo board has recently decided that they will now start charging owners of units that are leased a $500 leasing fee. The association does not incur any fees nor are they negatively impacted by these none owner occupied units. This is a new development and was not in any of the original documents that I signed when I purchased the unit several years ago. Is this legal and what if any legal rebuttal is available to me? The unit is located in Central NJ.