How Government Policies Utilize the Law of Demand

Every time petrol prices rise, fewer people take unnecessary drives. Every time a mobile recharge plan gets cheaper, more people upgrade their data pack. This everyday behaviour is the law of demand at work, and it is far too useful for governments to ignore. Ministries and regulators do not just watch this law play out passively. They use it deliberately, adjusting prices through taxes, subsidies, and price controls to nudge citizens toward outcomes the state considers desirable, whether that means cutting tobacco use, protecting farmer incomes, or making cooking gas affordable for low-income households.

A quick recap of the law of demand 🔗

The law of demand states that, all else being equal, the quantity of a good people buy moves in the opposite direction of its price. When price rises, quantity demanded falls. When price falls, quantity demanded rises. This relationship is captured by the downward-sloping demand curve that most economics textbooks open with.

What is easy to miss is one of the law’s own assumptions: it holds only when government policy on taxation, subsidies, and trade stays constant. In reality, that assumption rarely holds for long. Budgets change tax slabs every year, subsidy schemes get revised, and price controls are announced and withdrawn. Each time this happens, the government is effectively stepping into the demand curve itself, not just observing it.

Why price is such a useful policy lever 🔗

Governments have three broad ways to influence the price a consumer actually pays: taxing a good to push its price up, subsidising it to pull the price down, or fixing a legal price floor or ceiling that overrides the market outcome altogether. Which tool works, and how well it works, depends heavily on one factor: how sensitive demand for that good is to price. This sensitivity is measured through price elasticity of demand, and it decides whether a policy mainly changes consumer behaviour, mainly raises government revenue, or does both.

The objectives behind these choices usually fall into a few recurring categories. Discouraging consumption of goods that harm health, such as tobacco or alcohol, calls for taxation. Encouraging consumption of goods that benefit society, such as clean cooking fuel or education, calls for subsidies. Protecting the income of a vulnerable producer group, such as farmers, calls for a price floor. Keeping an essential good affordable for consumers during a shortage calls for a price ceiling. In every case, the government first has to think through how demand will actually respond to the new price, or the policy risks missing its target entirely.

Taxation: raising prices to reduce demand 🔗

The clearest example of tax-driven demand management in India is tobacco. Cigarettes, bidis, and other tobacco products are taxed heavily, partly for revenue and partly as a public health tool. Research on price elasticity of tobacco products in India found that demand elasticity varies a great deal across products, ranging from roughly -0.4 to close to -0.9, with bidis and leaf tobacco being far more price-responsive than cigarettes.

This variation matters for policy design. A study examining cigarette taxation after the rollout of the Goods and Services Tax found that cigarette demand in India is only mildly price elastic, with elasticity estimates as low as -0.196 in urban areas. In simple terms, even a fairly steep tax hike on cigarettes does not reduce consumption by much, because habitual smokers keep buying despite the higher price. Bidis behave differently. Because their demand is closer to unit elastic, a similar price increase produces a much sharper drop in quantity demanded, particularly among lower-income users who are most sensitive to price.

What this means for policymakers 🔗

When demand is inelastic, taxation is a strong revenue tool but a weak behaviour-change tool. When demand is elastic, the same tax becomes a genuine deterrent, though it also hits poorer, price-sensitive consumers harder. This is exactly why health economists keep pushing for uniform, steep tobacco taxes across all product categories rather than a lighter touch on cheaper products like bidis, which currently escape the heavier tax burden placed on cigarettes.

Subsidies: lowering the effective price to boost demand 🔗

If taxation pushes the demand curve’s price axis up, subsidies pull it down, and the law of demand predicts exactly what should happen next: quantity demanded rises. India’s LPG subsidy programme is a textbook illustration. Under the PAHAL direct benefit transfer scheme, domestic LPG cylinders are sold at the market price, and the subsidy amount is credited straight into the consumer’s bank account rather than being built into the retail price.

This design still respects the law of demand. The consumer’s effective price after the subsidy credit is lower than what they would pay without support, which keeps demand for clean cooking fuel higher than it would otherwise be, especially among households that might otherwise revert to cheaper, more polluting alternatives. Structuring the subsidy as a direct transfer rather than a blanket price cut also lets the government target the benefit at genuine users while reducing leakage through duplicate or fake connections.

Price floors and ceilings: overriding the market price directly 🔗

Sometimes the government does not just nudge the price through tax or subsidy. It sets a legal minimum or maximum price outright. The Minimum Support Price, or MSP, for 22 mandated crops is India’s most prominent price floor. The government commits to buying wheat, paddy, and other notified crops from farmers at a pre-announced price, generally set at least 50 percent above the cost of production, regardless of what the open market is offering that season.

A price floor set above the natural market price creates a predictable side effect. At that higher price, the quantity farmers want to supply exceeds the quantity private buyers want to demand, so a surplus builds up in the market. This is precisely why the Food Corporation of India and state agencies step in to procure the unsold surplus directly from farmers. The price floor does not cancel the law of demand; it simply guarantees that someone, in this case the government, absorbs the gap between what the market would naturally buy and what is being supplied.

Price ceilings work in the opposite direction and carry the opposite risk. When a maximum price is fixed below the market rate, such as caps on essential medicines or rent control in some cities, quantity demanded at that lower price tends to exceed quantity supplied, which can create shortages or push transactions into informal channels. Both tools show the same underlying lesson: any price set away from the market equilibrium changes how much of a good people demand, exactly as the law of demand predicts.

Consumer surplus: measuring the benefit that policy delivers or removes 🔗

Consumer surplus is the gap between the maximum price a buyer would have been willing to pay for a good and the price they actually pay. Economists describe it as the difference between willingness to pay and the market price, and it is a useful way to see who actually gains or loses when the government changes a price.

A subsidy such as the LPG DBT scheme increases consumer surplus, because households now pay less than they were willing to pay for the same cylinder. A tobacco tax does the reverse: it shrinks consumer surplus by pushing the price closer to, or above, what many consumers are willing to pay, which is exactly the discouragement effect the policy is designed to create.

Why elasticity changes the size of that surplus 🔗

Goods with inelastic demand, largely necessities that people keep buying regardless of price, tend to carry a larger potential consumer surplus, since a meaningful share of buyers would have paid considerably more if they had to. This is also why taxing inelastic necessities is controversial. It can raise substantial revenue precisely because people cannot easily cut back, but it also erodes welfare for consumers who have no real alternative. Subsidising the same kind of good, as with LPG, protects that surplus instead of taking it away, which is part of why essential-goods subsidies remain politically popular even when they are fiscally expensive.

Putting the tools side by side 🔗

Every one of these tools works because the government is, in effect, borrowing the same logic a shopkeeper uses when deciding whether to run a discount or raise a price tag. The difference is scale and intent. A shopkeeper wants more footfall. A government wants healthier citizens, food-secure farmers, and affordable energy access, and it reaches for the same lever, price, to get there.

What do you think? If a tax on an inelastic good raises significant revenue but barely changes consumption, is it still a fair policy tool, or does it just become a burden on people who have no real choice but to keep buying? And between taxing harmful goods and subsidising essential ones, which approach do you think does more to actually improve consumer welfare in the long run?

References

1. https://www.geeksforgeeks.org/microeconomics/law-of-demand/
2. https://academic.oup.com/heapol/article-abstract/23/3/200/602289
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC7928156/
4. https://www.pib.gov.in/PressReleasePage.aspx?PRID=2152413&reg=48&lang=2
5. https://www.pib.gov.in/PressReleasePage.aspx?PRID=2177219&reg=48&lang=2
6. https://corporatefinanceinstitute.com/resources/economics/price-floors-price-ceilings/
7. https://corporatefinanceinstitute.com/resources/economics/consumer-surplus/