As long as you have used, and can prove you have used all safety precautions, then you can use ladders. It is NOT illegal to use them, but if you have an accident, you will need to prove that you took every step (no pun intended) possible to prevent an accident.
That is why having a company policy on ladder use along with method statements and risk assessments covers your back, I can't stand all the paperwork, but unfortunately they are a necessary evil today.