PHOENIX — Saying their 5-year-old child's life may depend on it, a Phoenix couple has sued to demand legal access to extracts of marijuana for him.

Jacob and Jennifer Welton say Zander said the only thing that has helped control "numerous active seizures'' in the child who has birth defects that have affected development of his brain has been a mixture of chemicals from marijuana made in part from a hemp extract. They also said the drug combination they have made also has aided in addressing Zander's autism and physical development.

But a conclusion by state Health Director Will Humble that extracts may be illegal under the 2010 Arizona Medical Marijuana Act, coupled with similar decisions by prosecutors and threats of police action, have made that extract unavailable.

That has left the couple trying to feed Zander dried marijuana leaves which is "not palatable for anyone and is particularly hard for Zander given his physical limitations.'' And they said having Zander smoke the drug is not acceptable, at least in part because that would activate the psychoactive properties of marijuana that would make the child "high.''

So they want a Maricopa County Superior Court Judge to rule that the 2010 voter-approved law does allow patients like Zander, who has a doctor's recommendation and a state-issued card to use the drug, to obtain it in extract form.

The ultimate outcome of the case is likely to have implications far beyond Zander.

Both Maricopa and Pima County prosecutors are taking the position that dispensaries that sell extracts and patients that either use or make them are breaking the law. It is likely to take a ruling by the Arizona Supreme Court to resolve the issue.

In fact, the question is so complex that Amelia Cramer, the chief deputy Pima County attorney, said that patients who make a tea out of the marijuana leaves they legally acquire may be creating an "extract'' — and can be prosecuted.

But attorney Emma Andersson of the American Civil Liberties Union, said the prosecutors are off base.

"The Arizona Medical Marijuana Act, both the text and the intent, are clear that patients like Zander should be getting the best medicine possible for them,'' she said.

Humble acknowledges that the 2010 law clearly contemplates those authorized both to sell and use marijuana for medical reasons need not smoke it. Food products are legal.

But Humble said that, strictly speaking, the law legalizes only "usable marijuana.'' He said that requires any food products to contain actual pieces of marijuana.

More to the point, anything without the pieces is an extract. And that remains a felony.

That's the position of not only Maricopa County Attorney Bill Montgomery but also the Phoenix Police Department. And Andersson said that, in turn, has made it impossible for the couple to purchase the hemp oil they had been using before.

She said this is more than an issue of convenience and palatability. It goes to the numerous chemicals in the marijuana plant.

Andersson said it appears the best medication for Zander is a combination that is very high in cannabidiol and very low in tetrahydrocannabinol, in a ratio of 20 to 1.

The former is found in a hemp extract, typically called CBD oil. The latter contains the psychoactive elements of marijuana that provide the high.

The results, according to the lawsuit, go beyond a decrease in Zander's seizures.

"He is showing signs of wanting emotional stimulation and notices that people are people, not inanimate objects,'' the lawsuit states.

"Zander is seeking physical attention from his parents when he wants comfort or love,'' the legal papers continue. "He actively tries to play with his brothers and recognizes his parents' laughter and responds with his own laughter.''

His physical development also has improved, with Zander now able to walk backwards, avoid objects when walking and is nearly able to run.

Neither Humble nor Montgomery would comment about the lawsuit.

Cramer, however, said there may be other options for the parents, options which are legal.

For example, she said, the federal government already allows doctors to prescribe Marinol. The maker of this drug, derived from marijuana, says it is commonly used for loss of appetite associated with weight loss in patients with AIDS.

Andersson, however, said Marinol is high in THC.

"That's actually not the type of marijuana that is helpful to Zander,'' she said. "Zander needs to have an extract that is high is CBDs, which is a different cannabinoid.

There is another legal option: Ask lawmakers to alter the statute. While the measure was approved by voters and is off-limits to legislative repeal, it can be amended, with a three-fourths vote, to "further the purpose'' of the underlying measure.

That is exactly what happened earlier this year when legislators agreed to alter the law to allow marijuana onto college campuses, at least for the purposes of clinical trials.

Andersson, however, said she intends to argue that the law already contemplates — and allows — for extracts that are made into oils and food products.