I don't know how codes come into play here, and I'm just a homeowner, not an expert -- but I'm pretty sure that a properly installed drain line should be pitched enough that even a full ditch wouldn't back up into the garage. (If the road is under water, that's another story.)

IMO, it's more likely that your rain gutters are tied into the same drain line, and there's a clog somewhere between your house and the road (tree roots, collapsed pipe, or whatever).

For now, I'd run to the hardware store and get a sump pump and enough flexible pipe to reach lower ground. Use that to fight the standing water in the garage. When the rains let up, call a drain service, and have them run a camera through the pipe and see what they find.

Others here may have more ideas for you.

If the water really is coming up through the drain they do sell drain plugs. People around here who live in the flats do have water come up through the drains during heavy rains. The drainage sewers just can't handle all the flow and backs up the line. Even when the line is pitched.

Similar to what functionthenlook said, if the water is because of backflow into the garage from the drain, look into installing a backflow preventing valve in the garage drain. It will allow flow out but block water flow in.