Lawyers in Mexico expect a slew of lawsuits to be filed in response to the Mexican government's move May 15 blocking dozens of solar and wind projects ready to go online, halting more than a dozen others under construction and curbing production at existing private facilities that compete with the state-owned electricity company.

The government said its directive, published by the Energy Ministry, was made to ensure power supplies are not interrupted during the COVID-19 health crisis. But lawyers said it deals a death blow to private electricity generation, and a coalition of business chambers in the country labeled the move a "frontal attack on legal certainty of investments in Mexico." They said it will harm projects worth more than $30 billion.

The rules published Friday appear to be permanent, and lawyers and industry groups predicted a slew of lawsuits would follow.

"The private sector—including generators, sellers and energy consumers—will exhaust the legal resources offered by the Mexican constitution as well as trade agreements and international instruments," the Business Coordinating Council vowed Sunday.

Mexican legislators passed a law in 2014 that allows the generation and sale of electricity to occur in a free, open and competitive market. That law invited billions of dollars of investment from both domestic and international investors. Some large industrial users have already been producing their own electricity for years.

But Mexican President Andrés Manuel López Obrador (AMLO) has long opposed private investment in the country's energy sector and has sought to boost support for state energy companies since he took office in December 2018.

His administration has canceled bids on private oil exploration made possible by his predecessor, who created an opening up of the energy sector. It also has forced private firms to renegotiate contracts for natural gas pipelines.

Now, lawyers say, the government has issued highly restrictive rules for the electricity market in the name of national energy security.

"This is basically the u-turn we were all afraid that AMLO's administration would take in regards to the energy reform," said Daniel Sánchez, a partner with Baker McKenzie's corporate practice in Mexico City who specializes in energy.

Sánchez is already advising clients on their legal options, which include arbitration against the Mexican state via the International Centre for Settlement of Investment Related Disputes. That venue affords investors from countries that have trade agreements with Mexico to claim damages and lost profits from sovereign acts that are deemed unfair.

Mexico is party to multiple trade agreements, including the North American Free Trade Agreement (NAFTA) with the U.S. and Canada.

The Mexican government defended the electricity restrictions as a way to guarantee that electricity reaches end-users during the COVID-19 health emergency. The pandemic has drastically reduced electricity demand as countless factories and commercial properties went offline to comply with quarantine orders.

That unbalance between supply and demand "compromises the reliability and continuity of electric supply, especially to guarantee the operation of essential activities and the uninterrupted function of infrastructure and the health system during the emergency," the Energy Ministry said in a statement.

The state-owned electricity company, CFE, said the entry of renewable energy to the system needed to be delayed because those generators "produce oscillations and provoke interruptions" in the national electric grid.

Longer-term, lawyers and industry groups said the new rules will skew income to the state electric company while stoking consumption of fuel oil stockpiles from another ailing state company, the oil firm Pemex, thereby aiding the state.

The American Chamber of Commerce in Mexico expressed deep concern over the measure, saying it limits competition by favoring state companies. It also bemoaned the retreat from more sustainable and cleaner energy sources.

"Mexican consumers will be the most-impacted since rates will not respond to market forces, limiting access to competitive prices, which will affect the ability to retain and attract new projects," the Chamber said.

Affordable and reliable electricity is an essential business consideration for global manufacturers looking for places to produce goods.

The U.S. is Mexico's top source of foreign direct investment, having accounted for about 38% of inflows in recent years. Mexican government data shows the country has attracted $18.1 billion during the first half of 2019, with much of that foreign investment going to manufacturing.