Germany’s Federal Constitutional Court received a highly unusual complaint on Tuesday, with the country’s entire population of male piglets named as plaintiffs.

The piglets probably have no idea, but they could be about to write legal history, animal rights lawyers hope, even as critics decry the lawsuit as a PR stunt.

Amid a wave of efforts worldwide to allow animals to become plaintiffs, the current case is Germany’s first such constitutional challenge. It was filed by the People for the Ethical Treatment of Animals group — whose representatives also act as plaintiffs — and alleges that the German government is infringing upon the animals’ rights.

It is still unclear if the court will allow the case to proceed.

PETA argues that the castration of male piglets is violating German law, which states that animals shall not be harmed without reasonable explanation. The castration of young piglets without anesthesia was long considered exempt — but that exemption was withdrawn in 2013.

Castration without anesthesia is still in use, however, as the German government delayed the law from taking effect, following a transition period that was initially expected to last four years.

PETA alleges that in delaying the changes, the government is violating German law. It also alleges that even with anesthesia, the castrations will remain illegal, as they will not be completely pain-free, said Christian Arleth, a lawyer with PETA.

Besides seeking an end to the castration practice, PETA aims to get animals recognized as legal entities.

The legal status of animals has gradually expanded in Germany over the past decades, from their de facto perception as objects to their current status as organisms with rights protected by the Constitution. In parallel, the United States has seen a similar proliferation of legal protections for animals.

But in bringing the case before Germany’s highest court, animal rights lawyers still face an uphill battle. What remains controversial in both countries and elsewhere is how violations of animal rights can be brought to courts and whether animals can have their own legal standing.

So far, German animal rights cases were predominantly brought to regional state courts, where rights groups are in some cases explicitly allowed to represent animals’ interests. The Federal Constitutional Court, meanwhile, has so far focused on cases involving human plaintiffs or organizations operated by humans.

Animal rights lawyers argue that the most recent constitutional complaint could add pressure on the highest court to expand its interpretation of who or what can constitute a plaintiff.

The case has received some prominent backing, including from Berlin’s Tagesspiegel newspaper, which wrote in a commentary: “The existing legal system in Germany is so strong because it has evolved and has been revised.”

“In the Roman Empire, there were free humans and slaves — today, animals are our slaves,” the paper stated.

Critics of such litigation argue that accepting this rationale would trigger a wave of similar cases — creating billions of new potential plaintiffs and overwhelming the courts. It could also pose broader, delicate questions, such as whether animals accused of misbehavior could then also qualify as suspects.

Still, attempts to pave the way for an expanded plaintiff definition continue to be made, including in the United States.

Last year, an 8-year-old U.S. horse named Justice sued his former owner for negligence, seeking at least $100,000 for veterinary care plus damages.

The case was the latest in a series of similar complaints.

Some of them have circled around the question whether human slavery can be compared to stock farming. Other cases have sparked interest for less serious reasons.

Last April, an Indonesian monkey lost a high-profile case against a wildlife photographer, after PETA argued that David J. Slater — the owner of a camera the monkey used to snap selfies in 2011 — infringed upon the monkey’s copyright to the photos.

PETA argued it was acting as the monkey’s “next friend” — a claim that drew strong criticism. An appeals court later stated that PETA “failed” as the monkey’s “friend,” as the revenue from a settlement the organization had initially reached with the photographer did not benefit the monkey, but rather the group’s wider interests, the court argued.

“Puzzlingly, while representing to the world that ‘animals are not ours to eat, wear, experiment on, use for entertainment or abuse in any other way,’ PETA seems to employ Naruto as an unwitting pawn in its ideological goals,” the court wrote at the time, referring to the monkey’s name.

The animal rights group still celebrated the outcome last year as a general confirmation “that nonhuman animals have the constitutional right to bring a case to federal court when they’ve been wronged,” according to a statement by PETA general counsel Jeff Kerr.

Tuesday’s constitutional complaint takes the same fundamental question across the Atlantic to Europe.

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