New tariffs on some Canadian goods could roil Maine’s markets if they go into effect as planned next month, experts say.

The new import taxes were ordered by President Donald Trump last week. The U.S. will charge a 50% tax on the value of a wide range of goods from Canada, from wine to paper products to hockey equipment, beginning Aug. 19. Trump has used tariffs extensively since his second term as both bargaining chips in trade negotiations and as a revenue generator; he’s long called himself “a tariff man.”

The new tariffs won’t directly impact Maine’s biggest category of imports from Canada — energy — but could send shockwaves through exhausted supply chains that Mainers feel in their wallets. And the law Trump invoked to implement the new duties is as yet untested, meaning the president’s push could be challenged in the courts.

“It really has been incredible how volatile the situation’s been,” said Patrick Woodcock, the president and CEO of the Maine Chamber of Commerce.

Here’s what to know about the newest Canadian tariffs.

WHAT’S INCLUDED? WHAT’S NOT?

Unlike previous tariffs imposed under the second Trump administration, these duties are aimed at specific Canadian goods — not all imports.

Notably not included in the new tariffs: energy and fisheries — two of Maine’s biggest Canadian import categories.

Forest products, which Woodcock said are among the most important industrial ties between Maine and Canada, would be impacted if the tariffs go into effect on Aug. 19. To what level will vary from business to business.

“It does include some finished products, and that will have an impact,” he said. “But what we’re really watching is inputs into our finished product, like pulp, lumber.”

The tariffs specifically include several kinds of plywood, finished paper products and chemical wood pulp — the primary component in paper manufacturing. Also included are cars, dairy products, wine, beer, some machinery, hockey equipment, cement, furniture and dozens of other products.

It’s not a catch-all tariff, but it will be impactful for many businesses, University of New England associate economics professor Oak McCoy said.

“We’re not going to see this sort of economy-wide shock where we see prices go up 50%,” McCoy said.

However, he said, businesses unable to find alternatives could take a significant hit.

WHAT’S THE LAW TRUMP INVOKED?

Trump’s three tariff proclamations Monday cited the 1930 Tariff Act — the Smoot-Hawley Tariff Act, as it’s more commonly known — as the legal basis.

The Smoot-Hawley Act hiked tariffs, led to a worldwide trade war and is often credited with spiraling the Great Depression — a history lesson economists take to heart still today, McCoy said. Canada’s Prime Minister Mark Carney said Thursday he was prepared to respond if the tariffs go into effect next month.

“We restrict Canadian products, Canada restricts American products, and then what ends up happening is business and consumers on both sides end up with higher costs and fewer customers,” McCoy said.

But the Smoot-Hawley law has never been invoked in this way, a Congressional Research Service report found in March.

Section 338 of the law allows the president to issue retaliatory tariffs of up to 50% against countries whose own trade policy “discriminates” against American goods — either by targeted taxes on American companies or other some other regulation. No independent study or recommendation is required under the provision.

Trump’s proclamations ordering the new tariffs said Canada has been discriminating against American motor vehicles, dairy and alcoholic beverages — hence those industries’ inclusion in the new tariffs.

This new round of duties comes months after the U.S. Supreme Court rejected the president’s initial justification for his unilateral and wide-ranging import taxes. The court found he could not invoke new tariffs under the International Emergency Economic Powers Act.

A federal trade court also struck down Trump’s use of Section 122 of the Trade Act of 1974 — another never-before-used tariff provision — in May. That decision is under appeal, but those time-limited tariffs lapsed Friday.

To replace those duties, Trump issued new sweeping tariffs on Thursday of 10% on about 80 countries, including Canada, under a different section of the same 1974 law.

Most Canadian goods are exempt from the new 10% tariff because of the U.S.-Mexico-Canada Agreement, or USMCA, a free-trade pact between the three countries.

But the targeted 50% duties on Canada would bypass that agreement, the White House said.

Many Canadian products that have been exempt from import taxes will face tariffs for the first time — a potential shock for Maine businesses that have so far been sheltered by the USMCA, McCoy said.

HOW WILL MAINE BUSINESSES RESPOND?

Woodcock said the new tariff strategy — targeting specific Canadian goods for tariffs, instead of across-the-board charges — makes predicting the impact on Maine businesses more difficult.

Plus, Woodcock said he expects lawsuits and court orders, just like the other tariffs. Some Maine businesses may find the constant change difficult to adjust to, he said.

“These supply chains are pretty complicated,” Woodcock said. “Sometimes, (goods) come in from another third party, so they don’t know that their supply chain would be affected by this.”

McCoy said the long-term uncertainty is more impactful than the tariff costs themselves.

Companies may choose to delay their decisions until they understand the long-term impacts of new tariff policy, he said.

“It’s not simply that the rules are changing, but the businesses don’t know what rules they’re going to have to adhere to when it’s time to make that investment decision,” McCoy said.

The U.S. and Canada are currently negotiating a new version of the USMCA. Carney said Thursday in a news conference that he and Trump planned to renew talks over the coming weeks.

Depending on the outcome of those negotiations, Carney said, “everything’s on the table.”