As a person trained as a laser safety officer...
It's actually surprising what it is not illegal to do. However, if it is done in a workplace...
The main consideration is safety. If you place others at risk then you are going to find yourself liable. This is clearly a class 4 device, and I would encourage you to read up on safety precautions for class 4 device.
In Australia you can operate a device if it is class 1 in operation. For things like laser cutters (and this is where my experience is) then you have to ensure that the laser is fully enclosed and have interlocks or other technical means (this may simply be key locked panels) to prevent exposure to the beam.
Visible beams are particularly dangerous to your eyesight because you will automatically turn your gaze toward, and focus on an unexpected flash of light.
I encourage you to read a report by a person who had their sight destroyed by a laser. I'll try to find one. It describes the speed, the feeling, the sound, and the visual experience of the last thing you'll ever see clearly.
A safe enclosure for your laser may be as simple as a transparent yellow acrylic box. BUT you have to be certain of the attenuation of the material at the wavelength of your laser, and ensure that the physical construction prevents direct exposure to the enclosure of a focused beam.
