is not allowed to target other NAFTA citizens when they impose new measures. The NAFTA also stipulates that Canada must pay compensation for destroying investment by U.S. investors. Prime Minister Harper made a public promise that his government would not tax trusts, as had the previous Liberal government. Canada's tax treaty with the United States also says that trust income will not be taxed at more than 15%. The Gottliebs maintain a website for American and Mexican citizens interested in filing a NAFTA claim against the Government of Canada. Examples of publicly traded royalty trusts Baytex Energy Trust (Canada: oil and natural gas) BP Prudhoe Bay Royalty Trust (US: Prudhoe Bay oil field, Alaska) Canadian Oil Sands Trust (Canada: oil sands) Enerplus Resources Fund (Canada: oil and natural gas; properties both in Canada and the U.S.) Harvest Energy Trust Canada: 70% oil, 30% natural gas, and also owns a refinery) Permian Basin Royalty Trust (US: Texas, oil and gas) Penn West Energy Trust (Canada: oil and gas) Pengrowth Energy Trust (Canada: oil and gas, including oil sands) Precision Drilling Trust (Canada: drilling contractor to the oil and gas industry) Private energy income trusts Petrocapita Income Trust (Canada: western Canada, oil and gas) United States In the US, the business trust structure appeared with publicly traded partnerships (PTPs; also known as master limited partnerships or MLPs) which were limited partnerships with units that trade on public securities exchanges, combining the tax advantages of partnerships with the liquidity of public companies. PTPs started in the early 1980s in the oil and gas and real estate industries. As the decade went on, a variety of other businesses, from manufacturers to the Boston Celtics basketball team, began using the PTP structure . In 1987, there were more than 100 PTPs and Congress estimated that the trend was costing Washington $245 million a year in lost revenue. A law was enacted that treated PTPs as corporations unless they derived 90 percent of their income from so-called "passive sources", which included interest, dividends, capital gains, real estate rents, income and capital gains from real estate (e.g., developers and homebuilders), income and gain from natural resources activities, and commodities. All existing PTPs whose income did not qualify (roughly a third of them) were given 10 years before they would be taxed as corporations. Just like in Australia, many of these eventually changed structures, went off the market,