If you browse around all the immigration forums, this is a topic that always comes up and is a critical issue for a lot of people who plan to relocate for work to the US. To note these partner visas all apply to dependent children (usually have to be under 21) but in this post I will focus on the spouse. Also the requirements are very similar for each so I wont talk about each separately for the most part.
The E3D Visa is the partner visa of the E3 working visa for Australians. (to note the E3D holder does not have to be an Australian citizen)
The H4 is the partner visa of the H1B working visa.
The J2 visa is the partner visa of the J1 visa.
The L2 visa is the partner visa of the L1 working visa.
Now all of these barring the H4 visa do allow the holder to work providing they file form I-765 to the USCIS after entering the country. Usually it takes 2-3 months to receive the EAD card (employment authorization document) upon which time the holder can work.
The J2 visa generally only gets granted to spouses of J1 visa holders whom are here on some form of Internship program and thus generally here for 1-2 years. It is very unlikely a J2 visa granted for a spouse of a J1 holder whom is here on a Work and Travel or Camp USA type program. I know for a fact that many organizations in the visa sponsoring field were actually unaware that a J2 visa holder could work so may have to affirm this in interviews.
The H4 visa is the unfortunate visa of this quartet that has no work priviliges and it doesn’t seem likely anytime soon that it might change..although you never know. Now I know many H4 holders that do work both for organizations that know that it is illegal as well as organizations that are unaware. However it is officially illegal to do so, thus be aware of the risks of your actions.
There is not much else to say about the partner visas other than they have to fill similar forms (but not all) of the forms prior to the US Consulate interview as the primary visa holder. You don’t have to attend the consulate at the same time and can just bring a photocopy of the primary visa holder’s passport and visa but unless circumstances don’t allow it, I always would wonder why couples don’t attend interviews together.
The final point to make is that the United States DOES NOT recognize either defacto/common law couples or same-sex couples whom maybe defacto or married elsewhere. So if your partner wants to come to the US attached to your visa, they must be married to you and usually an original marriage certificate from your area will suffice.
I hope those that come here as couples enjoy the shared experiences together and that you have no problems in getting here to begin with. Honestly if your relationship is honest, you shouldn’t have an issue at all.