Sofia Vergara's ex-fiancé Nick Loeb has compared their embryo battle to the fight end ''slavery.''

The 45-year-old actress has been locked in a bitter lawsuit with the businessman since 2015 when he filed documents to protect, and bring to term, two female embryos, which they had created and planned to use with a surrogate during their relationship.

Nick, 42, has been blocked from bringing the embryos to term twice by the 'Modern Family' beauty, but he's now filed a third lawsuit claiming the debate over the cells being product or people has happened ''only one other time in United States history from which any legal precedent may be reviewed - the pre- Civil War era.''

According to the documents, obtained by website The Blast, Nick then went on to give the full legal definition of slavery and added: ''Under these simple definitions, a human embryo, if believed to be a human being and alive, (which is our contention) would be considered a slave and the parents would be the owners of the slave, particularly in states where they are considered property.''

But he didn't stop there as he also brought up the story of Solomon Northup, who was born a free man in New York and later abducted and sold into slavery.

He was eventually rescued near the Red River in Louisiana on a cotton plantation and his heartbreaking story was turned into the Oscar-winning film '12 Years a Slave'.

Nick explained: ''There was a question at the time as to whether New York had the jurisdiction to reach into Louisiana and retrieve Northup. But the New York governor discussed it with Louisiana officials and they were allowed to retrieve him. There are also dozens of cases (called the Freedom Suits), where slaves themselves or their family members applied for freedom in slave states and won.

''The reference to slave cases is to demonstrate the jurisdictional and legal issues arising from this stark difference in how human beings are categorised. In modern day, frozen human embryo disputes and the question of how they are categorised (human being or property) has become more frequent.

''Since there is little or no legislation in most states on this issue, state courts are left to decide if embryos are human beings or property or something in between and what to do in cases of dispute.''

Nick filed the lawsuit in Louisiana because officials there do consider embryos as human beings, whereas California - where they were created - calls them products.

Sofia argues that their suit, which was filed in January, has no connection to Louisiana and has pushed for it to be thrown out.

The judge is yet to make a decision on the matter.

Sofia and Nick - who split in 2014 after two years of dating - had signed a contract at the ART Reproductive Center in Beverly Hills when they created the embryos in 2013, which stated neither could use them without the consent of the other.

Sofia - who is now married to Joe Manganiello - was sued by the embryos in 2016, when a right-to-live lawsuit was filed on their behalf in Louisiana.