First, you will still owe income tax on any withdrawal. You can claim an exception to the 10% penalty for early withdrawal on up to $10,000, or half your account balance, whichever is less.
Second, workplace plans are not required to allow domestic abuse withdrawals. It is up to the plan and your employer whether they allow any hardship withdrawal, and what kind of hardship withdrawals.
Third, the IRS has not yet issued regulations about whether a DA withdrawal needs any kind of court certification. The law says "spouse or domestic partner"; the law does not say if it needs to be a registered domestic partnership. The law also says the withdrawal must be no later than 1 year from the date the abuse was suffered. (The law does not say whether it must be 1 year from the date of first abuse incident or 1 year from the date of the last incident.) As I said, the detailed regulations that might explain it better have not been written. For now, if your plan allows DA withdrawals, your plan is allowed to accept your self-certification that you qualify. Your plan should not ask for any other personal information about the situation except your self-certification.
And lastly, the law defines DA as,
The term “domestic abuse” is defined in section 72(t)(2)(K)(iii)(II) as
physical, psychological, sexual, emotional, or economic abuse, including efforts to
control, isolate, humiliate, or intimidate the victim, or to undermine the victim’s ability to
reason independently, including by means of abuse of the victim’s child or another
family member living in the household.
See here for more info and FAQs.
https://www.irs.gov/pub/irs-drop/n-24-55.pdf
