So long as the company has included a statement that policies can be changed at any time without notice to employees they should be able to legally change any policy without ramifications. That said, it is also important that employees trust the policies that you have in place and if they change often, or to the employees detriment, you could actually harm your relationship with employees when changes occur. Therefore it is recommended that pending changes are discussed with employees before being made, and that concerns are adequately addressed when possible before the policy goes into effect.