I am not quite sure what you mean by "lawyer-proof".
Do you mean that your safety has a key lock build in to it? If so, you can replace it with any non-keyed 870 safety.
If you mean that the trigger pull weight is too heavy for you, do you have an 870 Police? The 870P has a heavier sear spring which results in a heavier trigger pull weight. You can buy the spring that comes on the 870 Express and switch the two.
If you mean that your 870 trigger just feels heavy and gritty... is your 870 new? If so, shoot it a lot and it will probably smooth out. Otherwise, Brownells sells a trigger kit for the 870 which replaces several of the trigger group compnents and springs. Can't remember who makes it.
Here is a link to the kit: http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=21078&title=REMINGTON+870%2f1100+TRIGGER+SYSTEM